2021.06.23

2020 (Ku) 102

Decision concerning Article 750 of the Civil Code, Article 74, item (i) of the Family Register Act, and Article 24 of the Constitution

Case of special appeal to the Supreme Court against a decision to dismiss with prejudice on the merits an appeal against a ruling to dismiss without prejudice an appeal against a disposition made by a mayor of a municipality

Decision of the Grand Bench, dismissed with prejudice on the merits

Tokyo High Court, Judgment of November 25, 2019

The provisions of Article 750 of the Civil Code and Article 74, item (i) of the Family Register Act are not in violation of Article 24 of the Constitution.

(There are a concurring opinion, an opinion, and dissenting opinions.)

Article 24 of the Constitution, Article 750 of the Civil Code, and Article 74, item (i) of the Family Register Act

The Constitution of Japan
Article 24(1) Marriage shall be based only on the mutual consent of both sexes and it shall be maintained through mutual cooperation with the equal rights of husband and wife as a basis.
(2) With regard to choice of spouse, property rights, inheritance, choice of domicile, divorce and other matters pertaining to marriage and the family, laws shall be enacted from the standpoint of individual dignity and the essential equality of the sexes.

Civil Code
(Surname of Husband and Wife)
Article750 A husband and wife shall adopt the surname of the husband or wife in accordance with that which is decided at the time of marriage.

Family Register Act
Article 74 Persons who wish to marry shall submit a notification to that effect, entering the following matters in the written notification:
(i) the surname that the husband and wife will take;

The appeal is dismissed with prejudice on the merits.

The costs of the appeal shall be borne by the appellants of final appeal.

Concerning the reasons for appeal stated by the counsel for appeal, SAKAKIBARA Fujiko, et al.

1. The appellants made a notification of marriage while making an entry to the effect that "the husband adopts his surname and the wife adopts her surname" in the written notification of marriage. In response, the appellants received a disposition of non-acceptance (hereinafter referred to as the "Disposition") from the mayor of Kokubunji City. Therefore, the appellants filed this appeal to seek an order to accept the aforementioned notification against the same mayor under Article 122 of the Family Register Act. The Disposition was made on the grounds that the aforementioned notification is in violation of the provisions of Article 750 of the Civil Code stipulating that a husband and wife shall adopt the surname of the husband or wife in accordance with that which is decided at the time of marriage and the provisions of Article 74, item (i) of the Family Register Act that set forth the surname that a husband and wife take as a matter to be entered by persons who wish to marry in a written notification of marriage (hereinafter these provisions are referred to as the "Provisions"). The counsel's arguments include the argument that the Provisions are in violation of Article 14, paragraph (1), Article 24, and Article 98, paragraph (2) of the Constitution and are invalid.

2. However, the provisions of Article 750 of the Civil Code are not in violation of Article 24 of the Constitution, as held in the judicial precedent of this Court (2014 (O) No. 1023, the judgment of the Grand Bench of the Supreme Court of December 16, 2015, Minshu Vol. 69, No. 8, at 2586 (hereinafter referred to as the "2015 Grand Bench Judgment")). In light of the purport of the 2015 Grand Bench Judgment, it is obvious that the provisions of Article 74, item (i) of the Family Register Act, which specify the surname that a husband and wife take as a matter to be necessarily entered in a written notification of marriage in response to the provisions of Article 750 of the Civil Code, are also not in violation of Article 24 of the Constitution. Even taking into account various circumstances found in the decision in prior instance that have been observed since the 2015 Grand Bench Judgment, such as an increase in the rate of women who have jobs, an increase in the percentage of women in managerial positions, and other social changes, as well as an increase in the percentage of persons who agree with the introduction of the optional separate surname system and other changes in the awareness of citizens, it is not found that the determination in the 2015 Grand Bench Judgment should be modified. The counsel's argument of violation of Article 24 of the Constitution is not acceptable.

Incidentally, the issue of what system is reasonable as a legislative policy for the surnames of a husband and wife and the issue concerning the review of constitutionality, specifically, whether provisions on the same surname system in current laws are in violation of Article 24 of the Constitution and are invalid, exist in different spheres. The Provisions cannot be considered to be in violation of Article 24 of the Constitution and invalid at the time of the Disposition, as mentioned above. How this type of system should be designed is a matter that needs to be discussed and determined by the Diet, as pointed out in the 2015 Grand Bench Judgment.

3. Other arguments of the counsel are arguments of the unconstitutionality but are substantially arguments of a mere violation of laws and regulations or arguments that lack a premise, and do not constitute a ground for a special appeal.

4. Accordingly, the Court unanimously decides as set forth in the main text of the decision, except for the dissenting opinion stated by Justice MIYAZAKI Yuko and Justice UGA Katsuya and the dissenting opinion stated by Justice KUSANO Koichi. Incidentally, there is a concurring opinion of Justice MIYAMA Takuya, Justice OKAMURA Kazumi, and Justice NAGAMINE Yasumasa, and an opinion of Justice MIURA Mamoru.

The concurring opinion stated by Justice MIYAMA Takuya, Justice OKAMURA Kazumi, and Justice NAGAMINE Yasumasa is as follows.

We agree with the majority opinion that the Provisions cannot be considered to be in violation of Article 24 of the Constitution and that there is no need to modify the determination of the 2015 Grand Bench Judgment. However, we would like to make a few supplementary statements regarding the purport, etc. thereof.

1. First, the counsel argues that the Provisions make it a requirement for marriage that one of those who wish to marry changes his/her pre-marriage surname and a husband and wife use the same surname, thereby imposing a direct legal restriction on marriage.

Certainly, in response to Article 750 of the Civil Code, Article 74, item (i) of the Family Register Act specifies the surname that a husband and wife take as a matter to be necessarily entered in a written notification of marriage. A written notification of marriage is not accepted and marriage does not take effect unless this matter is entered (Article 739, paragraph (1) and Article 740 of the Civil Code). Therefore, in consideration of this point, the Provisions require the use of the same surname by a husband and wife as a requirement for marriage and thus can be considered to impose a restriction on marriage.

However, marriage mentioned here refers to legal marriage, and its particulars are expected to be provided for by law as matters pertaining to marriage and the family pursuant to Article 24, paragraph (2) of the Constitution. Article 750 of the Civil Code adopts the same surname system wherein a husband and wife adopt the surname of either one of them, as the effect of marriage, that is, as one of the particulars of the legal marriage system, and it provides that the surname that a husband and wife will adopt is decided at the time of marriage. On the other hand, in Japan, a legal system wherein the full name of a person and other matters concerning his/her status are entered in a family register and are notarized has been adopted, and Article 739, paragraph (1) of the Civil Code adopts the principle of notification-based marriage that marriage takes effect upon notification to make such entry into a family register. In response to these rules, Article 74, item (i) of the Family Register Act specifies the surname that a husband and wife take after marriage as a matter to be necessarily entered in a written notification of marriage. As a result of the particulars of legal marriage and the mechanism of formation thereof being specified as such by the Civil Code and the Family Register Act, the requirement of the use of the same surname by a husband and wife at the stage of formation of marriage has been imposed, and the aforementioned restriction should be described as an indirect restriction resulting from the effect of marriage and is not a restriction directly imposed on the act of marrying itself.

In addition, Article 24, paragraph (1) of the Constitution clearly stipulates matters such as whether to marry or not, and whom and when to marry, should be left to the decisions made by the parties freely and equally. Marriage mentioned here is also legal marriage, and it is just established as a package of legal systems. Based on this, even if both parties do not want to change their surnames and thus choose not to marry on the grounds that the same surname system, which is part of such legal marriage system, does not meet their wishes, this cannot be immediately considered as a ground for considering that the Provisions impose a restriction against the purport of Article 24, paragraph (1) of the Constitution.

Therefore, even if the use of the same surname by a husband and wife is considered as a requirement for marriage, it cannot be immediately said that the Provisions are in violation of Article 24, paragraph (1) of the Constitution. The 2015 Grand Bench Judgment can also be considered to have contained this purport.

2.(1) Therefore, as held in the 2015 Grand Bench Judgment, whether or not the Provisions are in violation of Article 24 of the Constitution should be determined from the perspective of whether or not the Provisions are unreasonable in light of the requirement of individual dignity and the essential equality of the sexes and fall under the case that must be considered to be beyond the scope of the Diet's legislative discretion by examining the purpose of the system adopted by the Provisions (the same surname system) and the influence that may be derived from adopting the same system.

Under the current same surname system, some persons who change their surnames at the time of marriage that they have used for a long period of time may feel a loss of identity or suffer various disadvantages in social life, and some would almost give up marrying to avoid such circumstances, as pointed out in the 2015 Grand Bench Judgment. We can also understand that in light of such actual conditions, some have the opinion that the optional separate surname system is more reasonable because the same surname system forces the parties to choose to change one party's surname against his/her will at the time of marriage or to give up marrying, and does not respect personal interests in pre-marriage surnames and almost imposes an unjust restriction on marriage. Moreover, there is also the opinion that introduction of the optional separate surname system should be examined as a measure that is taken from the perspective of promoting the formation of a gender-equal society or promoting women's performance in occupational life.

However, as held in the 2015 Grand Bench Judgment, the specific content of matters pertaining to marriage and the family is to be specified by related legal systems, and how to design such legal systems takes on an important meaning. Matters pertaining to marriage and the family should be decided while taking into consideration various factors in the social situation, including the national traditions and the citizens' sentiments, and by making a comprehensive assessment with a focus on the overall rules of the times in terms of the relationships between husbands and wives and between parents and children. Therefore, establishment of a legal system concerning the surname of a husband and wife, including establishment of related systems that rule a child's surname and the manner of creating a family register, etc., is left to the reasonable legislative discretion of the Diet. Based on this, even if there is the aforementioned opinion concerning the introduction of the optional separate surname system, it is difficult to determine that the Provisions are unreasonable in light of the requirement of individual dignity and the essential equality of the sexes and fall under the case that must be considered to be beyond the scope of the Diet's legislative discretion, when comprehensively taking into account various points concerning the nature and function of a surname, meaning of adoption of the same surname by a husband and wife, and use of a pre-marriage surname as a by-name (hereinafter referred to as "use as a by-name"), etc. pointed out in the 2015 Grand Bench Judgment.

(2) In addition, the counsel argues as follows: since the 2015 Grand Bench Judgment, there have been changes in circumstances, such as an increase in the rate of women who have a job, an increase in the number of dual-income households, and other social changes, as well as changes in the awareness of citizens concerning the introduction of the optional separate surname system, etc., adoption of written opinions requesting the introduction of the optional separate surname system, etc. at councils of local public entities, a rapid expansion of use as a by-name, and a recommendation from the Committee on the Elimination of Discrimination against Women, which was set up under the Convention on the Elimination of All Forms of Discrimination against Women that Japan ratified; and thus the same surname system has become unreasonable due to these changes.

Certainly, the rate of women who have a job and the number of dual-income households both have been increasing since the 2015 Grand Bench Judgment, and it seems that accompanying this trend, more women have come to suffer disadvantages in occupational activities due to their surname change at the time of marriage. In addition, the result of an opinion poll conducted by the Cabinet Office in 2017, etc. indicates changes in the awareness of citizens, such as an increase in the percentage of persons who agree with the introduction of the optional separate surname system. Furthermore, the councils of local public entities across the country have submitted written opinions requesting the introduction of the optional separate surname system or promotion of the Diet deliberation thereon to the State or related administrative authorities under Article 99 of the Local Autonomy Act. In the meantime, use as a by-name, including such use in a public document, has been further expanding and increasing. In general terms, we consider that the Provisions can come to be considered to be in violation of Article 24 of the Constitution beyond the scope of the aforementioned legislative discretion, depending on changes in circumstances concerning the reasonableness of this type of legal systems.

However, when talking about changes in the awareness of citizens, which are included in the aforementioned changes in circumstances that have occurred since the 2015 Grand Bench Judgment, the awareness of citizens is surely one of the important elements to be considered in establishing a legal system concerning marriage and the family, but the awareness of citizens is, in principle, to be evaluated and determined by the Diet, which consists of elected members who represent citizens. Leaving aside the situation where the awareness of citizens regarding a legal system can be said to be objectively clear enough, the current situation concerning the introduction of the optional separate surname system cannot be considered to be sufficiently clear. Therefore, even in consideration of this fact along with the aforementioned social changes, such as an increase in the rate of women who have a job, it is hard to say that the Provisions have come to be evaluated as being in violation of Article 24 of the Constitution.

Moreover, it is undeniable that expansion of use as a by-name reduces people's feeling of strangeness regarding adoption of separate surnames by a husband and wife and furthermore has an element of causing doubts about the meaning of adoption of the same surname by a husband and wife in the family register. However, basically, as held in the 2015 Grand Bench Judgment, it seems to largely have an element of easing disadvantages suffered by a person who changes his/her surname upon marriage to a certain extent.

We must say that we cannot come to find that the determination of the 2015 Grand Bench Judgment concerning compliance with Article 24 of the Constitution should be modified even in consideration of various circumstances that had occurred during the period from the day on which 2015 Grand Bench Judgment was rendered to the day on which the Disposition was made (March 6, 2018), including the fact that the councils of local public entities across the country submitted written opinions under Article 99 of the Local Autonomy Act and the fact that the Committee on the Elimination of Discrimination against Women also made a recommendation in 2016, in addition to the aforementioned points.

3. However, circumstances, such as the aforementioned changes in the awareness of citizens regarding the reasonableness of the legal systems and social changes, are matters that the Diet, the legislative organ, should constantly keep an eye on and deal with, and a recent growth in discussions on the introduction of the optional separate surname system should also be squarely faced by the Diet first. In this regard, both the 2015 Grand Bench Judgment and the majority opinion on this case point out that the manner in which a system concerning the surname of a husband and wife should be conducted, including whether to adopt the optional separate surname system, is just a matter that needs to be discussed and determined by the Diet.

As stated in the majority opinion on this case, the issue of whether adoption of the optional separate surname system is a reasonable legislative policy and the issue concerning the review of constitutionality, that is, whether the provisions on the same surname system in current laws are in violation of Article 24 of the Constitution and are invalid, originally exist in different spheres, and the determination of the 2015 Grand Bench Judgment and the majority opinion on this case to the effect that Article 750 of the Civil Code and the Provisions are not in violation of Article 24 of the Constitution does not preclude the Diet from holding discussions on the aforementioned legislative policy and drawing a conclusion thereon at all. Regarding a legal system concerning the surname of a husband and wife that includes whether to adopt the optional separate surname system, as well as related systems that rule a child's surname and creation of a family register, etc., it should be considered to be more suitable solution in line with the nature of the matter to leave this issue to a national debate, that is, to the democratic process, and decide on a reasonable system through an extensive study (see the concurring opinion of the Justice TERADA Itsuro in the 2015 Grand Bench Judgment). We expect that the Diet will hold serious discussions on this issue in line with various opinions of citizens over this issue and changes in social circumstances, etc.

The opinion stated by Justice MIURA Mamoru is as follows.

I agree with the majority opinion in conclusion. However, I express my opinion as I think that the laws are in violation of Article 24 of the Constitution in that they do not offer an option of use of separate surnames by a husband and wife in relation to the requirement for marriage under the Provisions.

1. Interests pertaining to the maintenance of a pre-marriage surname

A full name, from the viewpoint of society, functions to identify an individual by distinguishing him/her from others, and at the same time, from the viewpoint of the individual, it is the basis for a person to be respected as an individual and the symbol of his/her personality. In this respect, a persons' full name forms part of personal rights (see 1983 (O) No. 1311, the judgment of the Third Petty Bench of the Supreme Court of February 16, 1988, Minshu Vol. 42, No. 2, at 27).

On the other hand, separately from a given name, a surname generally reflects a certain personal status, such as a parent-child relationship, as part of the legal system concerning marriage and the family, and could possibly be changed along with a change in the personal status. Regarding the handling of a surname in marriage, a related mechanism is to be established in such overall legal system.

However, the meaning of a full name as part of the personal rights is not lost depending on the content of such law. A surname should be considered to have a mixed nature based on which it becomes an element of the legal system concerning marriage and the family, while focusing on being the basis for a person to be respected as an individual and the symbol of his/her personality, as well as functioning to identify an individual by distinguishing him/her from others in combination with a given name.

Even in the case where a change in the personal status in association with the change of a surname is marriage, which is chosen by one's own intention, that intention is not naturally accompanied by the intention to change his/her surname. In combination with a given name, a surname acquired by a person at the time of his/her birth comes to have stronger function to identify an individual by distinguishing him/her from others and also comes to have a deeper meaning as the symbol of his/her personality, as he/she grows older. It is thus obvious that the change of a surname at the time of marriage not only extremely impairs the credit and reputation of an individual before and after the change due to inhibition of identification and distinction of the individual but also causes serious disadvantages, such as causing the individual to have a sense of losing the symbol of his/her personality.

Therefore, interests pertaining to the maintenance of a pre-marriage surname at the time of marriage can be considered as an individual's important personal interests, leaving aside the issue of whether or not they are guaranteed as constitutional rights.

2. Freedom to marry

The 2015 Grand Bench Judgment states that Article 24, paragraph (1) of the Constitution clearly stipulates matters such as whether to marry or not, and whom and when to marry, should be left to the decisions made by the parties freely and equally. In addition to that, in 2013 (O) No. 1079, the judgment of the Grand Bench of the Supreme Court of December 16, 2015, Minshu Vol. 69, No. 8, at 2427, the court ruled that the freedom to marry is sufficiently worthy of respect in light of the purport of the provisions of the same paragraph. However, this ruling held the fact that the provisions of the Civil Code make a distinction between men and women in terms of the requirements for remarriage as a point to be considered in relation to the principle of equality under the Constitution and is considered not to limit the position of this freedom under the Constitution and the normative nature thereof.

Originally, whether to marry or not and whom and when to marry are not merely the choices of whether to use a legal system of marriage. Marriage is to choose a spouse with whom one should share and spend his/her subsequent life, and it is one of the most important decisions made by a person him/herself in relation to the pursuit of individual happiness. Even if marriage is premised on a legal system, the aforementioned purport pertaining to Article 24, paragraph (1) of the Constitution can be considered to be based on individual dignity and centered on the prohibition of unreasonable restrictions on autonomous decision-making by the parties.

Taking into account that Article 24, paragraph (1) of the Constitution clearly specifies that marriage shall be based only on the mutual consent of both parties, it should be said that setting of an unreasonable requirement for the formation of marriage by law in addition to the mutual consent of both parties will cause the issue of unconstitutionality. In that sense, it is considered that the freedom to marry is guaranteed by the same paragraph.

On the other hand, matters pertaining to marriage and the family are to be decided while taking into consideration various factors in society, by making a comprehensive assessment with a focus on the overall rules in terms of the relationships between husbands and wives and between parents and children. The task to establish a specific system addressing them is left primarily to the Diet's reasonable legislative discretion. However, this does not become a reason for denying the guarantee of the freedom to marry in the same manner as in the cases of other constitutional rights (regarding the property right, right to vote, etc., their content and system therefor are also to be specified by law under the Constitution).

In particular, as mentioned in the 2015 Grand Bench Judgment, Article 24, paragraph (2) of the Constitution provides that laws should be enacted from the standpoint of individual dignity and the essential equality of the sexes, thus defining the limits to the discretion. It is not permitted to take a legislative measure, etc. that unreasonably infringes personal rights that are guaranteed as constitutional rights. This requirement is obviously premised on paragraph (1) of the same Article in terms of both form and content, and individual dignity mentioned there can be considered to define the limits to legislation as an aspect that includes the meaning of giving a basis for the guarantee of the freedom to marry.

3. Restriction on rights and a framework for determination concerning the constitutionality

(1) Regarding the effect of marriage, Article 750 of the Civil Code provides that a husband and wife shall adopt the surname of the husband or wife. However, the same Article also provides that such adoption is "in accordance with that which is decided at the time of marriage" and is based on the premise that the surname to be adopted is decided at the time of marriage. Then, marriage takes effect upon notification pursuant to the provisions of the Family Register Act (Article 739, paragraph (1) of the Civil Code), and a husband and wife must submit a written notification of marriage while entering the surname that they will adopt therein (Article 74, item (i) of the Family Register Act). Therefore, persons who wish to marry cannot marry without deciding the surname that they will adopt and submitting a written notification in which the decided surname is entered. Therefore, in combination with Article 739, paragraph (1) of the Civil Code, the Provisions require the decision of a surname to be adopted by a husband and wife as a requirement for marriage, and it is thus obvious that the laws do not offer any other option.

Consequently, there is no other choice but for either one of the two to change his/her surname in order to marry. This means that the statutory requirement for marriage forces an individual to choose between marrying by changing his/her surname against his/her own will and not marrying against his/her own will, with regard to the individual's free decision-making. For a party who does not wish to change his/her surname at the time of marriage, impossibility of marriage without waiving personal interests pertaining to the maintenance of his/her surname is not the issue of whether or not the content of the legal system is in line with his/her will but is the issue of whether or not he/she loses important legal interests. This must be considered to impose a restriction on a free decision-making concerning whether to marry.

This restriction denies the formation of marriage without deciding the surname to be adopted by a husband and wife through a legal requirement, and it can be considered to be a direct restriction intended by the same surname system. The issue here is the reasonableness of a restriction on a freedom to marry imposed as a result of the absence of an option in law of use of separate surnames by a husband and wife, in relation to the requirement for marriage under the Provisions. As long as the reasonableness of a legal requirement becomes an issue in relation to a restriction on a constitutional right, it is necessary to conduct examination of the constitutionality according to the nature of the relevant right.

(2) As mentioned above, the freedom to marry is based on individual dignity and centered on the prohibition of unreasonable restrictions on autonomous decision-making by the parties. Individual dignity defines the limits to legislation as a basis on which a legal system should stand and is not merely a guideline for legislative discretion or an element to be considered.

Therefore, in this case, it is necessary to determine the reasonableness of a restriction on the freedom to marry from the perspective of whether the restriction is justified. That determination is premised on the mechanism of the whole legal system, and neither the propriety of individual mechanisms that are not related to this justification nor the legislative discretion is questioned. For example, the handling of a surname of a child born in wedlock is considered in relation to the justification thereof, such as whether or not this issue can be a circumstance that justifies not offering an option of use of separate surnames by a husband and wife under the mechanism for children born in wedlock. Considering various possibilities and the propriety of the handling of a child's surname in the case of offering such option beyond the aforementioned consideration is basically an issue that belongs to the scope of the legislative discretion and is considered not to affect the aforementioned determination.

Such legal system concerning marriage and the family is established in consideration of overall consistency, practical validity, etc. in light of various factors, such as social situation and the awareness of citizens. The aforementioned determination on reasonableness can vary proportionately to changes that depend on the situation of the times. However, this differs from the legislative discretion, which is not premised on the limits to constitutional rights. As long as the reasonableness of a restriction on the freedom to marry is questioned, the determination is a legal issue concerning constitutional guarantee in the same way as personal rights and equality under law and is not an issue that should be considered appropriate to be left to a democratic process.

(3) Taking into account the nature of the freedom to marry guaranteed by Article 24, paragraph (1) of the Constitution on the premise of the above and the fact that paragraph (2) of the same Article clearly specifies the requirement for enacting laws, regarding whether a restriction on the freedom to marry imposed by the requirement for marriage under the Provisions complies with the same Article, it is necessary to determine whether or not the restriction can be accepted as a reasonable one by comprehensively weighing the purport and purpose of the Provisions in the legal system concerning marriage and the family, the nature and content of the freedom, the form, degree, etc. of the restriction, and by taking into account the requirement of individual dignity and the essential equality of the sexes.

4. Constitutionality of the Provisions

(1) The 2015 Grand Bench Judgment indicates multiple points with regard to the purport and purpose of the same surname system pertaining to the Provisions (No. 4, 4.(1)A. of the same judgment). These points can be considered to be appropriately reasonable in the legal system concerning marriage and the family. However, the reasonableness that matters here is the reasonableness regarding whether or not the measure to basically make no exceptions to the same surname system is justified in relation to restriction on the freedom to marry. This can also be interpreted as the issue of a substantial relationship or balance between the purport and purpose of the same surname system and the measure to make no exceptions thereto. From such perspective, there are the following questions regarding the purport and purpose of the same surname system.

First, although a family, which is a constituent of society, is distinguished from others by deciding a single appellation for the family and externally notifying the public of it, the status of a group of people who live as a family has diversified to an extreme degree in the real world.

The current law limits the scope of family members who should adopt the same surname to a husband and wife who are Japanese nationals and their unmarried children as well as adoptive parents and children, and excludes persons in other personal status. However, circumstances surrounding marriage and the family have significantly changed with the change of the times over 70 years. With the significant progress of declining birthrate and the aging population, the tendency to marry late or not to marry has been growing. In addition, the numbers of divorces and remarriages have increased, and the percentage of households consisting of a husband, wife, and their children has significantly decreased. The composition of a household thus has diversified. The number of marriages between a Japanese national and a foreign national has also increased, and there are also children born between them. In fact, livelihood or nurturing of a child, etc. is sometimes supported by the actions of family members irrespective of the issue of whether family members use separate surnames or the same surname. The form of the family has become extremely diverse (in 2012 (Ku) No. 984 and No. 985, the judgment of the Grand Bench of the Supreme Court of September 4, 2013, Minshu Vol. 67, No. 6, at 1320, the court also points out that the form of marriage and the family has diversified to an extreme degree).

As the legal system concerning marriage and the family is widely related to society in general, it is highly required to be simply and clearly standardized. However, for that reason, I must say that the system has departed from the increasingly diverse real society over many years and that it has become difficult to explain a reasonable ground for the measure to basically make no exceptions to the system.

Second, even taking into account the meaning of people's feeling that they are members of a family by adopting the same surname and the unity of a family, it is considered that such feeling, etc. is, above all, largely acquired through mutual trust and accumulation of each member's efforts in daily life accompanied by various difficulties. These feeling and sense of unity, etc. can be left to the will of the members of each family according to the actual conditions thereof, and it is rather appropriate to do so in terms of nature. The reasonableness of the measure to make no exceptions to the same surname system cannot be explained on the premise of diversification of the form of the family.

Third, even taking into account the interests of use by a child born in wedlock of the same surname as his/her parents on the premise of the mechanism for children in wedlock, which is an important effect of marriage, such interests differ from specific rights and interests that form the basis for the nurturing of a child, such as presumption of a child in wedlock and joint parental authority (there are also no provisions on such interests in the Conventions on the Rights of the Child (Convention No. 2 of 1994)). In addition, viewing the meaning of the same surname system as a mechanism for showing a child to be a child in wedlock poses a risk of possibly promoting a sense of discrimination and discriminatory treatment in the relationship between children born in wedlock and those born out of wedlock. Moreover, denial of exceptions to the requirement for marriage means denying the aforementioned specific rights and interests granted to children born in wedlock. It is hard to say that especially protecting the aforementioned interests in the form of permitting no exceptions under the legal system, on the premise of diversification of the form of the family, gives the basis for the reasonableness in justifying a restriction on constitutional rights.

Incidentally, practice of using a pre-marriage surname as a by-name has recently been spreading in various forms, and such measures can ease, in part, disadvantages caused by the absence of an option of use of separate surnames by a husband and wife. However, these are voluntary measures for convenience and do not eliminate the essential problem relating to the personality of an individual. In addition, such spread of use as a by-name itself has resulted in accidentally indicating that the aforementioned points explained as the purport of the same surname system, etc., including a surname's external public notification and distinction functions as an appellation for a family, do not provide sufficient grounds at least for permitting no exceptions.

(2) A. On the other hand, the requirement for marriage under the Provisions is not a requirement pertaining to objective facts, such as the age of marriage and bigamy, but is a requirement concerning the parties' intention to decide the surname of a husband and wife. However, if either of the two persons is required to waive his/her important personal interests when they make a decision that has a significant meaning regarding the pursuit of their happiness as individuals, i.e., marriage and no exception is allowed to this requirement, this must be considered to be a substantial restriction imposed on a free decision in light of the requirement for individual dignity. In fact, there have also been cases where a couple inevitably chooses not to legally marry to avoid such disadvantages.

B. In addition, the Provisions literally do not prescribe discriminatory treatment based on sex. However, for many years, the overwhelming majority of persons who wish to marry have chosen the husband's surname as a result of individual discussions between them. In fact, many women have suffered disadvantages resulting from their surname change at the time of marriage. This fact clearly indicates the widespread existence among citizens of awareness and thinking that have caused an extreme bias in the choice of the surname of a husband and wife, and a doubt arises in the point that the choice of a surname is the result of a truly free choice made by both parties who wish to become a husband and wife.

In this regard, the 2015 Grand Bench Judgment determined that the same surname system has been established in the Japanese society since the enactment of the Former Civil Code (referring to Act No. 9 of 1898 prior to amendment by Act No. 222 of 1947). However, until the aforementioned amendment in 1947, a surname was considered as an appellation for a family, and the family system under which a wife, in principle, enters her husband's family through marriage had been adopted. That system was one that conflicts with the essential equality of the sexes as it restricted the wife's capacity to act to an extreme extent under law.

In addition, there is an argument that; the aforementioned amendment abolished the family system, but it established the principle of adoption of the same surname by a husband and wife and their children; as a result, the amendment failed to eliminate the awareness that the surname of the male line should be maintained and succeeded as an appellation indicating certain kinship. This is a reasoned argument. Furthermore, a stereotyped division of roles on the basis of gender (see Article 4 of the Basic Act for Gender Equal Society) based on the idea that a husband works outside and a wife keeps house and a sense of seeing such division of roles as correct spread throughout the high economic growth period. Although such sense has tended to be alleviated in recent years, it seems to be serving as a factor that supports the aforementioned tendency concerning the choice of the surname of a husband and wife in combination with a deep-rooted sense of maintaining the surname of a male, etc. It is also probably hard to deny the influence of these circumstances on the legislative process regarding this issue. It is also possible to say that the "establishment" of the same surname system has been achieved through the pains of many individuals over the years.

At any rate, as a practical matter, the same surname system clearly has the effect of causing disadvantages to women and is causing an extreme imbalance in terms of the substantial equality of the sexes. I must say that the restriction on the freedom to marry is a burden that is more close to compulsion for women who do not wish to change their surnames at the time of marriage.

C. Furthermore, after over 70 years, the values and awareness of citizens have significantly changed with extreme changes in social and economic circumstances, etc. during that period, and the lifestyle and the form of family life have diversified to an extreme degree. In particular, not only has the number of dual-income households extremely increased with an increase in the rate of women who have a job, but the number of women continuously engaging in social activities, etc. also significantly increased in various fields. Therefore, the interests pertaining to the maintenance of a pre-marriage surname have taken on a desperate importance.

In present-day Japan, it is a matter of urgent importance to realize a society in which men and women respect each other's human rights and share responsibilities, and every citizen is able to fully display their individuality and ability regardless of gender. For that purpose, it is necessary to ensure that social systems and practices have as neutral an impact as possible on the selection of social activities by men and women (see Preamble and Article 4 of the Basic Act for Gender Equal Society).

D. Looking at the international trend, the Convention on the Elimination of All Forms of Discrimination against Women (Convention No. 7 of 1985; hereinafter referred to as the "Convention on the Elimination of Discrimination against Women") was adopted in 1979, and Japan also ratified it in 1985. The Convention obliges States Parties to eliminate all forms of discrimination against women, including indirect discrimination (Articles 1 and 2) and also obliges States Parties to eliminate discrimination against women in relation to the same right to enter into marriage only with their free and full consent as well as the same personal rights as husband and wife, including the right to choose a family name (Article 16, paragraph (1)(b) and (g)). In general recommendations, the Committee on the Elimination of Discrimination against Women stated that each partner has the right to choose his or her surname and that when by law or custom a woman is obliged to change her surname on marriage, she is denied that right. Furthermore, in the concluding observations on the periodic report of Japan, the same Committee has repeatedly recommended amendment to the provisions of law so that women can continue to use their pre-marriage surnames.

As of 1947, many countries had adopted a system in which a husband and wife adopt the same surname. However, after going through the adoption and enforcement, etc. of the Convention on the Elimination of Discrimination against Women, there is no country acceding to the same Convention, except for Japan, that is now adopting a system that obliges a husband and wife to use the same surname.

The legal system concerning marriage and the family is established in light of factors such as the social situation and the awareness of citizens of each country. However, in light of the universality of human rights and the purport of Article 98, paragraph (2) of the Constitution, it is also necessary to take into account the situation concerning international rules as mentioned above.

(3) In the case of offering an option of use of separate surnames by a husband and wife, it is necessary to decide the handling of a surname of a child born in wedlock under the mechanism for children born in wedlock and the manner of creating a family register of a husband and wife who use different surnames and their children. For these matters, policy considerations and determinations are required. About a quarter of a century has passed since the Legislative Council made a report of the "Outline of the Bill for the Act Partially Amending the Civil Code" in 1996, and during that period, discussions have been held on various occasions, and the aforementioned recommendations, etc. have been made. However, the Diet appears to have hardly conducted specific consideration and discussions. Therefore, the aforementioned points do not give a ground for justifying the failure to offer an option of use of separate surnames by a husband and wife.

(4) Under the aforementioned circumstances, with regard to the Provisions, the situation where the freedom to marry is restricted in law due to the absence of an option of use of separate surnames by a husband and wife must be considered to have already been unreasonable at the time of the Disposition in light of the requirement of individual dignity and the essential equality of the sexes.

Therefore, the fact that law does not offer an option of use of separate surnames by a husband and wife in relation to the requirement for marriage under the Provisions, that is, the fact that the Diet has not taken prescribed measures to establish this option, is in violation of the provisions of Article 24 of the Constitution.

5. Acceptance of a notification of marriage

Even if the Provisions involve the aforementioned issue of the unconstitutionality, the fact remains that there are no legal provisions on the option of use of separate surnames by a husband and wife in relation to the requirement for marriage.

Regarding how to treat a surname in marriage, a related mechanism is established in the whole legal system concerning marriage and the family. The Provisions stipulate, as part of such mechanism, the effect of marriage and the matters to be entered in a written notification on the premise of a husband and wife taking the same surname. In consideration of the content and nature of the Provisions, it may be possible to judge that the Provisions are unconstitutional and invalid because what is stipulated in the Provisions offers only one option for a surname taken upon marriage, but it is unreasonable to go beyond this and consider that the effect of marriage and the matters to be entered in a written notification on the premise that there is another option would necessarily be added to that mechanism.

In addition, a notification of marriage is the requirement for marriage (Article 739, paragraph (1) of the Civil Code) and also becomes a basis for the creation of and entries in a family register (Articles 15 and 16 of the Family Register Act). A family register is to be created for each unit consisting of a husband and wife, and any children thereof with the same surname (Article 6 of the same Act). Therefore, in order to create an option of use of separate surnames by a husband and wife, it is necessary to review the fundamentals of the system, that is, the manner of creating a family register, in light of the rules on a child's surname. In addition, it is necessary to stipulate the matters to be entered in a written notification and the clerical work related to the family register to be conducted based on the notification, etc. (see Articles 13, 14, and 16, etc. of the same Act) in order to conduct clerical work related to the family register after confirming the choice of a husband and wife concerning their surnames. The Diet must promptly take necessary legislative measures for the whole legal system including these matters.

As long as such measures have not been taken, in terms of both the content and nature of the Provisions and the whole legal system, it cannot be said that there are rules for the option of use of separate surnames by a husband and wife through interpretation without the provisions of law. Therefore, it must be said that a notification by a written notification in which the surname that a husband and wife will adopt is not entered cannot be accepted (Article 740 of the Civil Code).

If marriage is considered to become effective by such notification, it is equal to establishing a legal system involving a defect of lack of law concerning an important part with regard to matters pertaining to marriage and the family, which results in causing due confusion in society. This should be considered as an interpretation not assumed by law.

For the reasons described above, the determination of the court of prior instance that the appeal filed by the appellants should be dismissed without prejudice can be accepted in the conclusion.

The dissenting opinion stated by Justice MIYAZAKI Yuko and Justice UGA Katsuya is as follows.

Unlike the majority opinion, for the following reasons, we think that the court should quash the decision of the court of prior instance and order acceptance of a written notification of marriage submitted by the appellants as the Provisions are in violation of Article 24 of the Constitution.

1. Concerning Article 24, paragraph (1) of the Constitution

(1) Purpose and purport of Article 24, paragraph (1) of the Constitution

A. Article 24, paragraph (1) of the Constitution provides as follows: "Marriage shall be based only on the mutual consent of both sexes and it shall be maintained through mutual cooperation with the equal rights of husband and wife as a basis." This paragraph is considered to be provisions that specifically stipulate the purport of Article 13 and Article 14, paragraph (1) of the Constitution in relation to the formation and maintenance of marriage on the premise that the same purport also applies to marriage. In 2013 (O) No. 1079, the judgment of the Grand Bench of the Supreme Court of December 16, 2015, Minshu Vol. 69, No. 8, at 2427 (hereinafter referred to as the "Grand Bench Judgment on the Period of Prohibition of Remarriage"), the court held that Article 24, paragraph (1) of the Constitution "clearly stipulates that" the parties' decision to marry "should be left to the decisions made by the parties freely and equally." There is also the same sentence as this in the 2015 Grand Bench Judgment. It is considered that the idea that the parties' decision to marry must be made freely and equally is derived from the purport of Article 13 and Article 14, paragraph (1) of the Constitution. Therefore, in the same manner as the right set forth in Article 13 of the Constitution, the provisions of Article 24, paragraph (1) of the Constitution include the purport of prohibiting the State's unjust interference with such decision, and whether or not the State's interference is unjust is determined based on whether it is considered to be justifiable as a restriction based on public welfare.

The provisions of Article 24, paragraph (2) of the Constitution, "laws shall be enacted from the standpoint of individual dignity and the essential equality of the sexes," indicate the requirement or guideline that laws to specify matters concerning marriage and the family should be enacted from the standpoint of individual dignity and the essential equality of the sexes, also on the premise of paragraph (1) of the same Article, thus defining the limits to the legislative discretion in the enactment, revision or abolition of laws pertaining matters concerning marriage and the family (see the 2015 Grand Bench Judgment). These "limits to the legislative discretion" are considered to mean that such laws must not be in violation of Article 13 and Article 14, paragraph (1) of the Constitution and must also not be in violation of the purport of Article 24, paragraph (1) of the Constitution in relation to marriage and that even if such laws are not considered to be against these provisions of the Constitution, they must not contain any provision that infringes individual dignity and the principle of the essential equality of the sexes in any part.

B. In 1959 (O) No. 1193, the judgment of the Grand Petty Bench of the Supreme Court of September 6, 1961, Minshu Vol. 15, No. 8, at 2047 (hereinafter referred to as the "1961 Grand Bench Judgment"), regarding the purpose of Article 24 of the Constitution, the court held that the same Article "provides for individual dignity and the principle of the essential equality of the sexes, which are the fundamental principles of democracy, in relation to marriage and the family and prohibits unequal treatment between a husband and wife in relation to enjoyment of rights on the grounds of being a husband or wife because men and women are essentially equal." The interpretation of Article 24, paragraph (1) of the Constitution mentioned in A. above is also in line with the 1961 Grand Bench Judgment.

C. We further specifically consider the issue in light of the aforementioned purpose. A restriction on the formation of marriage imposed by law must not be one that denies respect for the personalities of individuals who wish to become a husband and wife and is required not to suppress decisions that should be made by the parties freely and equally, in order to say that imposition of such restriction does not fall under the State's unjust interference with a decision to marry, which should be made by the parties freely and equally, in light of the purport of Article 24, paragraph (1) of the Constitution.

D. In light of the point that in marriage, both parties should be in a relationship in which they are mutually respected as individuals, it is safe to say that the "rights" mentioned in the provisions of Article 24, paragraph (1) of the Constitution, "with the equal rights of husband and wife as a basis," naturally include not only the property right covered by the determination in the 1961 Grand Bench Judgment but also personal rights (including personal interests). Then, there are literally no grounds for considering that such "rights" are limited to constitutional rights. Originally, regarding constitutional rights, citizens can naturally enjoy rights referred to in Article 13 of the Constitution as individuals without discrimination by gender, irrespective of whether or not they are married. Therefore, it is hard to consider that the purport of this part of Article 24, paragraph (1) of the Constitution is to daringly provide for the principle of equality only in relation to those who have become a husband or wife. The following understanding is rather in line with the purport of especially establishing these provisions concerning marriage: such "rights" include personal rights that are important from the perspective of respect for individuals or individual dignity that should underlie marriage, irrespective of whether such personal rights fall under constitutional rights under other provisions of the Constitution; the provisions prohibit unequal treatment in which only a husband or wife enjoys such "rights" while the other does not enjoy them only because he/she is a husband or wife.

E. In the determination concerning property rights in the 1961 Grand Bench Judgment, the court held that the part of the provisions of Article 24, paragraph (1) of the Constitution, i.e., "with the equal rights of husband and wife as a basis," means "to expect that a husband and wife in a marital relationship enjoy substantially equal rights when observing continuous marital relationship as a whole." However, even in light of this holding, the provisions of law that result in the situation where a husband and wife cannot expect to equally enjoy their personal rights, respectively, only on the grounds of marriage despite absence of legitimate grounds, such as the fact that enjoyment of personal rights by both a husband and wife unjustly infringes a third party's rights or goes against public welfare, are considered to be against the purport of Article 24, paragraph (1) of the Constitution, when taking into account that the idea of division cannot be applicable to personal rights.

F. Marriage itself is not a service provided by the State but is a human behavior that has been naturally established in society as a combination aimed at the lifetime cohabitation of both parties and has been recognized in society with a certain form. We think that marriage referred to in Article 24, paragraph (1) of the Constitution should be considered to have such meaning. If it is necessary to impose restrictions on the formation, effect, and content of marriage by laws and regulations for various reasons, it is necessary to individually examine each of such restrictions to confirm that it is not one that is unreasonable and unjustly precludes the parties from making decisions concerning formation of marriage in the aforementioned sense freely and equally against the purport of Article 24, paragraph (1) of the Constitution. The determination in the Grand Bench Judgment on the Period of Prohibition of Remarriage to the effect that the restriction based on the period of prohibition of remarriage referred to in Article 733, paragraph (1) of the Civil Code is unconstitutional was just the result of such examination. However, if a relevant restriction is found to be reasonable after such examination, imposition of that restriction on marriage by law does not go against the purport of Article 24, paragraph (1) of the Constitution.

G. For example, the procedural system that requires a notification to a municipal mayor for the formation of marriage itself can be considered necessary for specifying rights and obligations associated with marriage and is also necessary for the State to perform its responsibilities for realization of those rights and obligations. Therefore, imposition of the obligation to notify is a reasonable restriction on marriage and can be considered not to be against the purport of Article 24, paragraph (1) of the Constitution. In addition to that, we have no objection to restrictions, such as prohibition of bigamy and prohibition of marriage between close relatives by blood, being imposed as reasonable restrictions from the perspective of public welfare.

H. However, in the case where a specific restriction imposed in the marriage system under the Civil Code is found to unjustly infringe a decision to marry made by the parties freely and equally against the purport of Article 24, paragraph (1) of the Constitution, that restriction should be considered unconstitutional and invalid to the extent that it causes that infringement. In the case where such unconstitutional and invalid restriction is included in the restrictions provided by the Civil Code, a decision to marry made on the given premise of complying with that unconstitutional and invalid restriction cannot be considered as a decision to marry that is made freely and equally in line with the purport of Article 24, paragraph (1) of the Constitution. In addition, we have no objection to the point that how to design legal systems takes on an important meaning with regard to matters pertaining to marriage and the family. However, it is not reasonable to consider that an unconstitutional and invalid restriction should be considered constitutional for this reason.

I. For the reasons described above, we think that marriage referred to in Article 24, paragraph (1) of the Constitution must be marriage under the marriage system provided by Civil Code from which unconstitutional restrictions, including the same paragraph, are excluded.

(2) Requiring the use of the same surname by a husband and wife as a requirement for acceptance of a written notification of marriage is construed as a direct restriction on marriage

A. Article 74, item (i) of the Family Register Act provides that the surname of either husband or wife must be entered in a written notification of marriage as the "surname that the husband and wife take," and specifies this entry (hereinafter referred to as "entry of a single surname") as one of the matters to be necessarily entered in a written notification of marriage. In this case, the appellants submitted a written notification of marriage in which they did not make an entry of a single surname but instead entered their wish to adopt their own native surnames, respectively (hereinafter referred to as the "Written Notification of Marriage"). In response, the municipal mayor made the Disposition of not accepting the Written Notification of Marriage on the grounds of a failure to make an entry of a single surname. Therefore, marriage based on the Written Notification of Marriage has not been formed. In the 2015 Grand Bench Judgment, the court determined that the use of the same surname by a husband and wife is one of the effects of marriage and does not fall under a direct restriction on marriage. However, in light of the aforementioned development pertaining to non-acceptance of the Written Notification of Marriage, the appellants argue that requiring an entry of a single surname (that is, use of the same surname by a husband and wife) as a requirement for the formation of marriage in relation to the appellants falls under a direct restriction on marriage.

B. We consider the case on this point. First, looking at Article 74, item (i) of the Family Register Act that obliges an entry of the "surname that a husband and wife take" in a written notification of marriage, together with Article 739, paragraph (1) of the Civil Code that provides that "marriage shall take effect upon notification pursuant to the Family Register Act," it is clear in context that the provisions stipulate that an entry of a single surname is required for acceptance of a written notification of marriage and that the legal effect of marriage occurs by the acceptance of a written notification of marriage, that is, marriage is formed thereby.

C. Incidentally, the issue of whether or not this requirement for acceptance is a direct restriction on marriage is the issue of compliance with Article 24, paragraph (1) of the Constitution, which provides for the formation of marriage. Therefore, it is necessary to examine the meaning of this requirement for acceptance based on the understanding that such "marriage" has the same meaning as "marriage" referred to in the same paragraph as mentioned in (1)I. above. Then, in this case, imposition of a restriction requiring an entry of a single surname (use of the same surname by a husband and wife) for acceptance of a written notification of marriage on the appellants must be considered to suppress the appellants' decision to marry and preclude the appellants from making decisions freely and equally, as mentioned in detail in (4) below. As long as it is true, in this case, such restriction can be considered to fall under a direct restriction on marriage.

(3) Concerning the origin and nature of personal interests argued by the appellants in this case

A. The appellants argue that the aforementioned requirement for acceptance is a direct restriction on marriage by citing the fact that personal interests in the native surnames of the appellants are infringed if the use of the same surname by a husband and wife is made a requirement for the formation of marriage. Therefore, the origin and nature of these personal interests are examined here. In the 2015 Grand Bench Judgment, the holding that seems to express the court's idea on this point is probably the following in the determination concerning whether the "freedom from being forced to change one's surname" at the time of marriage falls under rights guaranteed under Article 13 of the Constitution: a surname has a meaning, separately from a given name, and the particulars of personal rights concerning a surname should be understood specifically only on the basis of a legal system.

However, for the following reasons, we have different opinions from the 2015 Grand Bench Judgment regarding both the point that a surname is discussed separately from a given name and the point that personal rights concerning a surname should be understood specifically only on the basis of a legal system.

B. Today, a full name consisting of a surname and a given name is recognized as the name of an individual. In determining whether requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage is a direct restriction on marriage, the origin and nature of personal interests in a full name should just be taken into account in consideration of the following: [i] a full name has a far more advanced function to distinguish oneself from others and a stronger self-identification function than a surname alone; [ii] it is said that a name came to be generally made up only of a surname and a given name in the Meiji Era and that before then, there were a variety of compositions of a name; however, the use of a name to distinguish an individual from others should be considered to be a practice that had been spontaneously conducted in society, irrespective of the constituent elements thereof; therefore, it cannot be said that the function to distinguish an individual from others and self-identification function of a full name (name) is not recognized without the legal system; [iii] the personal interests in a full name as argued by the appellants in this case are those derived from the fact that a full name (name) has the advanced function to distinguish an individual from others and a self-identification function, as mentioned in C. below: [iv] the change of a surname due to marriage automatically leads to the loss of identity between a pre-marriage name and a name used after marriage; as a result, it inevitably causes a serious impact and confusion in relation to both distinction of an individual from others and self-identification by him/herself (recognition of personality). Therefore, the essence of the problem included in this issue cannot be accurately understood only by discussing a surname separately from a given name.

C. The personal interests concerning a full name argued in this case are derived from the advanced function to distinguish an individual from others possessed by a full name (name), of which one of the constituent elements is a surname, and refer to the situation where a full name, as one aspect of said function to identify an individual, also functions to identify personality that is established by the personal and autonomous behavior of a relevant person as a human even in terms of him/herself, and it consequently becomes the symbol of identity and becomes part of personality. These are included in the personal interests mentioned in (1) above and are rights related to one aspect of an individual's personality that forms the basis of respect for individuals and individual dignity. Therefore, they are considered to be guaranteed under Article 13 of the Constitution. Consequently, the act of causing loss of these rights by law without the voluntary consent of a principal falls under unjust infringement of the rights unless it can be considered to be justifiable as a restriction based on public welfare. In this manner, these personal interests are neither rights created by law nor interests granted by a legal system or reflective interests of a legal system, and they arise from personal and autonomous behavior as a human. Therefore, the facts that a person cannot freely choose his/her surname under the legal system and his/her surname is determined at birth based on rules under the legal system cannot become a reason for denying these personal interests.

D. In the 2015 Grand Bench Judgment, the court held that the particulars of personal rights concerning a surname should be understood specifically only on the basis of a legal system. However, it is not that the legal system stipulates the particulars of these personal interests, and the particulars of these personal interests can be understood as one aspect of personality that is the basis of respect for individuals and individual dignity, as mentioned in C. above. Therefore, what is understood specifically based on the legal system is not the particulars of these personal interests but is merely the particulars of a restriction imposed on these personal interests by the legal system. In light of the idea mentioned above, in this case, the court is required to examine whether or not a restriction imposed on a surname or full name by law constitutes unjust infringement of the personal interests that have the aforementioned nature and particulars. Therefore, in this case, it is necessary to question whether or not a restriction imposed by the Provisions, which is to require the use of the same surname by a husband and wife as a requirement for the formation of marriage, is reasonable and is justifiable as a restriction based on public welfare after making clear the origin and nature of the personal interests in a full name.

(4) Concerning the meaning of a restriction imposed by the Provisions, including Article 750 of the Civil Code

A. Requiring the use of the same name by a husband and wife as a requirement for the formation of marriage means requiring a husband or wife to make a decision to accept the loss of the personal interests at the same time of making a decision to marry

(A) In this case, for the following reasons, the appellants submitted the Written Notification of Marriage, in which they did not make an entry of a single surname but entered their wish to adopt their own native surnames after marriage: if one of the parties changes his/her surname in association with marriage, due to the change, the pre-marriage name held by the party so far, which can be publicly confirmed in the family register, is extinguished, and as a result, the party loses his/her native name, which is the basis for respect for a person as an individual, is the symbol of the personality of the individual, and has been part of the personal rights; the party thus loses the personal interests linked to his/her native name, such as identity; in addition, as the fact of change of a full name (name) caused by the surname change due to marriage is not naturally recognized and disseminated in society, it results in inhibiting the recognition of identity of an individual in society and thereby causes infringement of personal interests; for example, in a manner that reputation of the relevant individual linked to his/her surname before change is impaired.

(B) For those who wish to maintain their native surnames, which have been the symbols of their personalities, respectively, after marriage, such as the appellants, requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage means that a decision to marry is not legally recognized as a decision to marry unless it is made at the same time as a decision to accept the loss of the aforementioned personal interests (which is against the principal's wishes).

B. Requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage means creating a situation where a husband and wife cannot enjoy equal rights after marriage and only one of them continues to bear a burden

(A) In this case, the appellants also point out the inability of a husband and wife to equally enjoy their own personal rights as the problem of the same surname system from the following perspective: under the same surname system, the parties cannot marry unless one of them accepts the infringement of the personal rights in his/her native name and the loss of his/her identity, while the other party can enjoy the personal rights concerning his/her native name without any restriction thereon.

(B) There is no holding referring to this problem in the 2015 Grand Bench Judgment. However, certainly, requiring an entry of a single surname in a written notification of marriage as a requirement for the formation of marriage means the creation of a situation where, as a result of marriage, only one party continues to enjoy the personal interests in his/her native name, while the other party cannot enjoy such personal interests for him/herself and continues to bear a burden caused by the loss of those personal interests. It is obvious that such one-sided inequality does not change and cannot be changed as long as marriage continues. In other words, requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage necessarily creates the situation where a party who changes his/her surname due to marriage cannot even expect to enjoy such personal interests equally with the other party, that is, the situation where due to the same surname system, he/she cannot share such personal interests equally because he/she has become a husband or wife through marriage, as long as marriage is maintained.

C. In this case, a decision to marry that is to be made freely and equally is suppressed by requiring the use of the same surname by a husband and wife as a requirement for formation of marriage

(A) Our idea about the nature of the personal interests in a full name is as mentioned in (3) above. From that standpoint, for persons who both refuse to accept the loss of identity caused by the loss of his or her native name and wish to use his or her native name, such as the appellants, imposition of a restriction by requiring an entry of a single surname (use of the same surname by a husband and wife) as a requirement for the formation of marriage is equal to [i] ordering one party who changes his/her surname to make a decision to marry after accepting infringement of the personal interests in his/her native name as a premise and [ii] ordering both parties, irrespective of whether being a party who will change his/her surname, to make a decision to marry on the premise that part of his/her own personality or the other party's personality is denied and they cannot equally enjoy their personal interests as long as marriage is maintained. This means that a decision to marry made by the parties is not legally recognized as a decision to marry unless the parties make it at the same time as a decision to accept the premises mentioned in [i] and [ii] above against their will. However, as mentioned in (3) above, these personal interests, in terms of nature, fall under personal rights related to one aspect of an individual's personality that forms the basis of respect for individuals and individual dignity. Therefore, if a decision to marry is not legally recognized unless the parties agree to accept a restriction on their rights against their free will, it can never be said that a decision to marry is a decision made by the parties freely and equally.

(B) We also have no objection to the point that a decision to marry can be recognized as a decision made by the parties freely and equally if the parties give voluntary consent to the change of the surname of one of them ([i] and [ii] mentioned in (A) above are the effects thereof). However, the appellants have not given voluntary consent to the change of the surname of one of them and have made clear in the Written Notification of Marriage that they have no intention of giving consent thereto. Therefore, for persons who both wish to use their native surnames after marriage, such as the appellants, imposition of a restriction by requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage suppresses decisions to marry to be made by such persons and the appellants and precludes them from making a decision freely and equally. Therefore, it must be considered to constitute infringement that goes against the purport of Article 24, paragraph (1) of the Constitution.

Incidentally, for the following reasons, the aforementioned conclusion is not affected by the fact that the same surname system stipulates that those who wish to become a husband and wife choose the surname that they will adopt based on an equal agreement between them: such agreement is only an agreement made on the condition that those who wish to become a husband and wife must accept the use of the same surname by a husband and wife as a given requirement for the formation of marriage; and as an option to allow both parties to adopt their native surnames, respectively, is not supposed to exist from the beginning, the result of such agreement cannot be considered to be based on a decision made freely and equally from the perspective of those who wish to use their native surnames after marriage.

(5) Unjustness of infringement mentioned in (4) above

A. Even if a restriction is imposed on the formation of marriage by requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage, which would produce a result that goes against the purport of Article 24, paragraph (1) of the Constitution, and thereby suppressing a decision to marry to be made by the parties and precluding the parties from making a decision freely and equally, if the restriction is justified based on reasonableness from the perspective of public welfare, it is possible to consider that the restriction by requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage cannot be considered to be the State's unjust interference that goes against the purport of the same paragraph. Therefore, this point is examined next.

B. The requirement for the formation of marriage, an entry of a single surname (use of the same surname by a husband and wife), which is the issue in this case, is a restriction imposed based on the same surname system provided in Article 750 of the Civil Code. Therefore, examining whether the fact that a surname has a meaning as an appellation for a family, which is cited as a reason for the reasonableness of the same surname system in the 2015 Grand Bench Judgment, can give the basis for the reasonableness of this restriction from the perspective of public welfare, it should be said that the idea that a surname has a meaning as an appellation for a family originally has no constitutional ground. (When we look back, there was also a time when the separate surname system was adopted in Japan. It is generally known that the separate surname system was changed to the same surname system in association with adoption of the "family" system by the Former Civil Code enforced in 1898, and that the same surname system was maintained though the "family" system was abolished with the enactment of the current Constitution. Under the Former Civil Code, a surname was an appellation for a "family," and as a result, a husband and wife came to use the same surname. However, it does not appear that sufficient discussions were held on the constitutionality of the same surname system in the course of enactment of the current Constitution, which is not premised on the "family" system.)

C. Next, the concept of a family has not been defined in either the Constitution or the Civil Code, and its extension is not clear. That concept has many meanings from a common sense perspective. Under the Family Register Act, a family register is created in units of a husband and wife and their unmarried children who adopt the surname of their parents. However, it is not that such unit alone is socially recognized as a family. It can be said that, even after marriage, the word "family" is naturally used as a concept that can include the parents, grandparents, and brothers and sisters of a person from common sense. Even today, a surname can be used even as an appellation for a "family" in the sense of a family line. In addition, the number of households consisting of a husband and wife and their unmarried children is decreasing further and further, and the actual conditions of households are diversifying. Under such circumstances, based on the idea that only a household consisting of a husband and wife and their unmarried children is considered as a family, the fact that a surname has a meaning as an appellation for such family cannot be considered to serve as a reasonable ground for denying the personal rights concerning a full name.

D. On the other hand, Article 24, paragraph (1) of the Constitution is considered to be provisions intended to guarantee not only the freedom to marry but also the freedom to divorce and remarry on the other side of the coin. The Civil Code also has no provisions that restrict divorce or remarriage by agreement of the parties. Under the family system provided in the Civil Code, there is a rule that a child born in wedlock of parents who are legally married uses the surname of the parents. On the other hand, parents having a child are not at all restricted from divorcing, remarrying to someone else, respectively, and also repeating those acts. Consequently, it is naturally assumed and accepted in the system under the Civil Code that a child's surname differs from his/her real parents' surnames or even a surname of a person who seems to be a family member living together with the child due to the divorce or remarriage of his/her parents, without relation to the child's will. This indicates that the Civil Code does not always require that a child's surname and his/her parents' surname are the same. In consideration of this point, a family in which a child's surname and his/her parents' surname are the same is considered to be merely one prototype (unenforceable model) of various forms of a family that is permitted to exist in diversified forms. Actually, the number of households consisting of a husband and wife and their unmarried children has been decreasing further over time, and the actual conditions of households and families have diversified to an extreme degree. It is not uncommon that a child's surname and a surname of a person who lives with him/her as a family differ from each other. Therefore, we consider that the infringement of the personal interests cannot be justified only because a surname has a meaning as an appellation for a family only in relation to such prototype form of a family. This is because a surname cannot be considered to have substance as an appellation for a family in relation to the other forms of a family.

E. We do not also deny that a surname has an aspect as an appellation for a family. However, as we have already mentioned, there is no ground for positioning that aspect as a constitutional requirement, and it makes no sense that a reasonable ground for denying the personal rights concerning a full name is considered to exist in the explanation that is cited in the 2015 Grand Bench Judgment as a reason for the reasonableness of the same surname system, that is, "a surname has a meaning as an appellation for a family." In addition, all the other points cited as the explanations of the reasonableness of the same surname system in the same judgments (a surname functions to externally notify the public that a man and woman are a husband and wife and distinguish them from others, indicates that a child is a child born in wedlock, makes a person feel that he/she is a member of a family, and makes it easy for a child to enjoy benefits from the use of the same surname as both parents) can be considered to grasp part of the image of a husband and wife or parents and their child assumed in the Civil Code, but they can hardly be considered as reasonable grounds for the same surname system in light of the reality of diversification of family forms as mentioned above and the permissive basic attitude of the Civil Code that assumes and accepts the diversity of family forms.

F. Therefore, we consider it impossible to say that it is reasonable from the perspective of public welfare to suppress decisions to marry to be made by the parties who wish to avoid the loss of the personal interests in their native names and enjoy equal personal interests as a husband and wife, such as the appellants, by requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage, thereby infringing decisions to marry that are to be made by the parties freely and equally.

Given this, the Provisions should be considered to go against the purport of Article 24, paragraph (1) of the Constitution in forcing the parties who wish to marry and to adopt their own native surnames after marriage, such as the appellants, to use the same name and obliging them to make an entry of a single surname in a written notification of marriage.

G. In addition, marriage is originally a private affair and information that falls under privacy. Although the parties are free to make public their marriage, the act of notifying the public of marriage despite the parties' unwillingness to make it public can constitute infringement of privacy. To the contrary, the act of externally notifying the public of the fact of being a child born in wedlock by a "surname" can be considered to have a negative effect of promoting discrimination against children born out of wedlock and children in divorced single-mother families. There are some legal benefits of being a child born in wedlock, including being subject to the joint parental authority of real parents. However, a child can enjoy those benefits if a means for publicly certifying the legal marriage of his/her parents is available, and it is not that a child can enjoy the benefits on the grounds that the surname of his/her parents is the same. It is hard to consider that it is difficult to stipulate a means for publicly certifying the legal marriage of parents in law in the same manner as in foreign countries if the same surname system is determined to be unconstitutional.

H. Incidentally, it is true that whether it is felt that the act of forcing a husband and wife to use the same surname constitutes an infringement of the personal rights varies between individuals. However, this does not become a reason for denying in this case that a restriction by requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage constitutes infringement of the personal interests in a native name and a decision to marry that is to be made freely and equally, which goes against the purport of Article 24, paragraph (1) of the Constitution. This seems to be clear in consideration of privacy rights. What is felt as infringement of privacy varies between individuals. For example, not a few persons make public the fact of having gotten an intractable disease, while there also seems to be not a few persons who want no one know such fact. For the latter persons, the benefit of not making public the fact of having been affected with an intractable disease should be constitutionally guaranteed as a privacy right, and even if there are some persons who do not care that the fact is known to others, the existence of such persons does not deny the guarantee of the interests of persons who want no one know the fact as a privacy right.

2. Concerning Article 24, paragraph (2) of the Constitution

(1) The determination framework differs, and the conclusion differs accordingly

A. Regarding matters pertaining to marriage and the family, Article 24, paragraph (2) of the Constitution provides that "laws shall be enacted from the standpoint of individual dignity and the essential equality of the sexes." Incidentally, the 2015 Grand Bench Judgment indicated the following determination framework: when the legal provisions on the same surname system do not violate Article 13 or Article 14, paragraph (1) of the Constitution, determination as to whether or not said provisions can also be accepted as being in compliance with Article 24 of the Constitution should be made comprehensively by examining the purpose of the legal system and the influence that may be derived from adopting the legal system, etc. and by considering whether or not the provisions in question should inevitably be deemed to be unreasonable in light of the requirement of individual dignity and the essential equality of the sexes and be beyond the scope of the Diet's legislative discretion.

B. However, for the reason mentioned in 1. above, we consider as follows: for persons who have made clear their disagreement with the same surname system in a written notification of marriage, such as the appellants, imposing the same surname system as a requirement for the formation of marriage suppresses decisions to marry to be made by the parties and thereby falls under the State's unjust interference that precludes them from making decisions to marry freely and equally, and it thus goes against the purport of Article 24, paragraph (1) of the Constitution; therefore, this case lacks a prerequisite for applying the aforementioned determination framework indicated in the 2015 Grand Bench Judgment; consequently, in this case, a determination cannot be made based on that determination framework; if law goes against the purport of the same paragraph, that law cannot be considered to be a law enacted from the standpoint of individual dignity and the essential equality of the sexes as referred to in paragraph (2) of the same Article only on that basis and to that extent and it thus deviates from the legislative discretion.

C. Thus, requiring an entry of a single surname (use of the same surname by a husband and wife) in a written notification of marriage as a requirement for acceptance of a written notification of marriage by applying the Provisions, including Article 750 of the Civil Code that provides for the same surname system, to the case where both parties wish not to change their own native surnames, and thereby requiring the use of the same surname by a husband and wife as a requirement for the formation of marriage falls under the State's unjust interference with decisions to marry to be made by the parties. Therefore, the Provisions go against the purport of the Article 24, paragraph (1) of the Constitution to that extent. Consequently, the Provisions cannot be considered to be laws enacted from the standpoint of individual dignity and the essential equality of the sexes as referred to in Article 24, paragraph (2) of the Constitution to that extent, and the Provisions deviate from the legislative discretion and must be considered to be unconstitutional. Our opinion is originally not that a husband and wife should be obliged to use separate surnames without exception but that it is unconstitutional that laws make no exception to the same surname system. In this regard, our opinion is to the same effect as the opinion stated by Justice KIUCHI Michiyoshi in the 2015 Grand Bench Judgment.

(2) Even based on the determination framework held in the 2015 Grand Bench Judgment, the Provisions should be determined to be in violation of Article 24 of the Constitution in consideration of subsequent changes in circumstances

Even if whether or not the same surname system complies with Article 24 of the Constitution is comprehensively determined by the determination framework held in the 2015 Grand Bench Judgment from the standpoint that the personal interests in a native name do not fall under constitutional rights and that the Provisions cannot be immediately considered to stipulate the requirement for the formation of marriage that goes against the purport of Article 24, paragraph (1) of the Constitution, we should additionally take the three points mentioned below (A., B., and C.) into account as circumstances that were not appropriately taken into account in the 2015 Grand Bench Judgment in determining whether or not the same surname system complies with the same Article in this case. If those points are appropriately taken into account, we would reach the conclusion that the Provisions that stipulate the same surname system are in violation of the same Article because the Provisions should inevitably be deemed to be unreasonable in light of the requirement of individual dignity and the essential equality of the sexes and go beyond the scope of the Diet's legislative discretion at the time of the Disposition at the latest.

A. The same surname system is a system that creates a condition that does not comply with individual dignity and the essential equality of the sexes

(A) In 1.(4)B. above, we pointed out that the same surname system is a system that creates a situation where a husband and wife cannot equally enjoy their personal interests in a full name. However, from the standpoint that the personal interests in a full name as argued by the appellants in this case do not fall under the rights guaranteed under Article 13 of the Constitution, these personal interests in a full name are rights and interests that are at least the same in quality and equal to the rights and interests that were held as part of personal rights in 1983 (O) No. 1311, the judgment of the Third Petty Bench of the Supreme Court of February 16, 1988, Minshu Vol. 42, No. 2, at 27. As long as that is true, it is impossible to deny that these personal interests are related to the core of the personality of an individual (if not, no one would feel the loss of identity). Therefore, what we pointed out in 1.(4)B. above is applicable as it is. Consequently, we have to say that the same surname system is a system which produces a result that goes against individual dignity and the essential equality of the sexes in this regard.

(B) In the determination concerning compliance with Article 24 of the Constitution in the 2015 Grand Bench Judgment, the court does not mention the existence of such problem in the same surname system at all. Therefore, we should say that this point is required to be taken into account in this case as a circumstance that was not taken into account in the same judgment. Considering this point together with the fact that the percentage of married couples in which a wife changes her surname reaches about 96%, after all, it is real that about 96% of married couples are in the state of gender inequality wherein it is a wife that loses the personal interests in her native name due to the same surname system and is kept in a state of inequality in the relationship with her husband.

(C) Incidentally, Article 24, paragraph (2) of the Constitution does not only provide that matters pertaining to marriage and the family are matters to be stipulated by law but also clearly specifies that laws shall be enacted from the standpoint of individual dignity and the essential equality of the sexes. Despite that, as mentioned above, it is difficult to consider that the same surname system, which produces a result that goes against the purport of both individual dignity and the essential equality of the sexes, is a system established from the standpoint of individual dignity and the essential equality of the sexes as is clearly specified in Article 24, paragraph (2) of the Constitution.

B. The expansion of the use of a pre-marriage surname after the 2015 Grand Bench Judgment is causing the loss of substance of reasonableness of the same surname system

(A) Originally, even if the fact that a surname has a meaning as an appellation for a family is the reason for the reasonableness of the same surname system, looking at the actual conditions of married couples and families, a household consisting of a husband and wife and their unmarried children is no longer considered to be a typical household. According to the statistics conducted in 2018, households consisting of a husband and wife and their unmarried children accounted for less than 30%, and households consisting solely of a husband and wife also accounted for less than 25%. Recent trends, such as an increase in the percentage of unmarried persons, a rise in the age of first marriage, an increase in the number of divorces and remarriages, and an increase in the number of international marriages, will continue in the future, and the percentage of households consisting of a husband and wife of Japanese nationals and their unmarried children is expected to further decrease. In addition, regarding the significance that children feel themselves as members of a family through the use of the same surname as their parents, there is no empirical evidence showing that a sense of unity of family weakened in foreign countries where the same surname system was abolished. Moreover, there is also no empirical evidence showing that the bond of a family in which a husband and wife substantially use separate surnames has weakened due to the use of a pre-marriage surname as a by-name. Although it is important to consider the welfare of not only a husband and wife but also children, there are occasionally cases where a married couple submits a written notification of divorce to formally divorce without intention to change the actual condition of marriage only for the purpose of restoring the native surname of a party who once changed it due to marriage, as well as cases where both of the persons who wish to marry cannot tolerate losing personal interests in their native names due to the change of their own surnames and choose de facto marriage. Taking into account the seriousness of disadvantages suffered by children in such cases (in the former case, children cannot receive benefits that children born in wedlock can receive under law as they are not treated as children born in wedlock; in the latter case, if parents get divorced, their children cease to be subject to joint parental authority and one of their parents becomes a person who has parental authority), we cannot overlook the point that the legal system that forces the use of the same surname by a husband and wife somewhat produces children who suffer such disadvantages and impairs the welfare of children.

(B) While the actual conditions of society regarding the points argued as the grounds for the reasonableness of the same surname system have been changing as mentioned above, measures to make it easy for women to use a pre-marriage surname as a by-name have been adopted one after another since the 2015 Grand Bench Judgment. Out of those measures, we think that the measure to make it possible to use a pre-marriage surname as a by-name even in preparing a public document at a national government organ is a significant change in circumstances that qualitatively dilutes the grounds for the reasonableness of the same surname system that were found in the 2015 Grand Bench Judgment.

(C) Originally, use of a pre-marriage surname as a by-name only resolves the loss of the personal interests in the native name of a party who changed his/her surname due to marriage and disadvantages caused thereby to a certain extent, and even if use of a pre-marriage surname as a by-name expands, there will be the cases where a public certification is necessary. Therefore, the fact that a pre-marriage surname can be used as a by-name does not become a ground for the reasonableness of the same surname system. Permitting the use of a pre-marriage surname as a by-name is rather just to find that the same surname system itself is unreasonable. It is of extreme importance that the expansion of the use of a pre-marriage surname as a by-name means the expansion of the social recognition of the fact that a full name entered in a family register after the change of a surname based on the same surname system is sometimes not fit for use in society, in other words, the fact that unless an individual uses a full name with his/her native surname, not with a surname under the same surname system, the individual may possibly be placed in an unreasonable and irrational situation that he/she would never experience if having married without changing his/her surname.

(D) In particular, the fact that it has become possible for a person who prepares a public document at a national government organ to use his/her pre-marriage surname as the name of a person who prepared the document that is to clarify the locus of responsibility for preparation of the document means that the national government organ has come to recognize that there is no problem even if a surname decided under the same surname system becomes a surname that is not used in real society (that is, a surname that is only entered in a family register that is, in principle, not disclosed) and that a pre-marriage surname has more substantial value than a surname decided under the same surname system and does not cause any legal problem in distinguishing a person responsible for the preparation of a public document from others also in relationship with citizens. This can be considered to indicate that the fact that a surname changed based on the same surname system has poor substantial value in terms of external public notification has also come to be recognized in society. The ground for the reasonableness of the same surname system that was held in the 2015 Grand Bench Judgment was mainly that a reasonable meaning can be found in that a surname is externally publicly notified. In light of this, the fact of the expansion of the use of a pre-marriage surname can be considered to make the explanation on the reasonableness of the same surname system valueless and clearly show the unreasonableness of the same surname system itself.

(E) In addition, the expansion of the use of a pre-marriage surname means that a pre-marriage surname is also used for nameplates and mails and that the state in which separate surnames are used by a husband and wife and by parents and their children expands. However, in particular, it is safe to say that permission of the use of a pre-marriage surname at a public organ has the effect of promoting private companies and organizations to permit the use of a pre-marriage surname with the progress of women's participation in society and also has the effect of encouraging women who wish to avoid the disadvantages of the same surname system to any extent to use their pre-marriage surnames. As a result, the number of married couples who use separate surnames in society increases, and it becomes impossible to distinguish such married couples from de facto married couples because those couples come to have no difference in appearance. The fact of being a husband and wife or being a family is not publicly notified by using a surname decided under the same surname system (a surname in a family register). Thus, the situation where a surname is externally not used to distinguish those who are a husband and wife or are family members expands. On the other hand, even if a surname decided under the same surname system is entered in a family register, personal information entered in a family register is privacy information and it is neither permitted to inspect a family register nor is a third party, in principle, permitted to request the issuance of a transcript or extract of a family register. Therefore, it is actually impossible to adopt the explanation that a family register becomes a means of externally notifying the public of a surname decided under the same surname system. In this manner, it has become undeniable that the expansion of the use of pre-marriage surnames has brought about the spread of the actual conditions that do not meet the explanation on the reasonableness of the same surname system and that the reasonableness of the same surname system has been qualitatively worn thin.

(F) In addition, the use of a pre-marriage surname as a by-name is substantially the same as permitting a married woman to use two names. However, for a person who uses his/her pre-marriage surname, it is not that the loss of the personal interests has not existed as long as he/she uses two names. Therefore, the essential problem caused by the change of a surname is not resolved, and the problem of the additional burden of using either of two names depending on the situation newly occurs. In addition, regardless of sex, an increase in the number of individuals who use two names also produces unreasonable results, such as an increase in the social cost of managing two names (for example, companies and organizations must manage two names for one employee, which requires costs) and an increase in the risk of an error in distinguishing an individual and cost thereof.

(G) For the reasons as mentioned above, it is even safe to say that the spread of use of a pre-marriage surname has already made the basis of the grounds for the reasonableness of the same surname system valueless both from the perspective of husbands and wives who use their pre-marriage surnames and from the perspective of the parties who wish to use separate surnames after marriage. Overlaying this fact on the fact that the same surname system is a system involving the problem of being a system that creates a situation where a husband and wife cannot equally enjoy their personal interests in their full names as pointed out in 1.(4)B. above, the legal system called the same surname system cannot be considered reasonable from the perspective of individual dignity and the essential equality of the sexes.

C. Based on the fact that Japan received the third formal recommendation requesting a legal amendment concerning the same surname system under the Convention on the Elimination of Discrimination against Women in 2016, it is strongly presumed that the same surname system is beyond the Diet's legislative discretion

(A) The Convention on the Elimination of Discrimination against Women entered into force in 1981. Japan concluded the Convention in 1980, and the Convention was ratified by the Diet and was also promulgated in 1985. In Japan, pursuant to Article 98, paragraph (2) of the Constitution, a convention is considered to come to have a domestic effect at the time of its promulgation. If a convention provides for the obligation of States Parties by a text that is legally binding to States Parties, that obligation is considered to have a binding effect on the government, legislative body, and judicial branch, which are national government organs. Therefore, regarding the Convention on the Elimination of Discrimination against Women, the legislative body also has the obligation to sincerely comply with the same Convention by revising and abolishing laws that are in violation of the obligations provided in the same Convention and by avoiding enactment of new laws that are against those obligations, as long as the provisions of the same Convention are stated by a legally binding text.

(B) Article 2 and Article 16, paragraph (1) of the Convention on the Elimination of Discrimination against Women provide as follows, thereby stipulating that States Parties themselves have the obligation to ensure the prescribed rights by taking necessary measures (development of domestic law): "States Parties … agree to … undertake"; "States Parties shall take … appropriate measures … ensure …." Incidentally, there is no room for question in that the use of the terms, "agree to," "shall," "undertake," and "ensure" in a convention indicates that the text of the convention is legally binding. For the Convention on the Elimination of Discrimination against Women, the Arabic, Chinese, English, French, Russian, and Spanish texts are equally authentic (that is, the Japanese text is merely a tentative translation). In the English text, the provisions of Article 2 of the same Convention are stated by using the phrase "agree to," and the provisions of Article 16, paragraph (1) are stated by using the term "shall." Therefore, it is clear that the text of the Convention is to make the provisions legally binding.

(C) Incidentally, as these provisions do not grant any right directly to Japanese nationals, the provisions are considered to be unlikely to be directly applied to citizens. However, this does not become a ground for denying that these provisions have a domestic effect. This is because in today's international jurisprudence, the possibility of direct application is not the premise of a domestic effect, and to the contrary, a domestic effect is generally considered as the premise of the possibility of direct application.

(D) In Article 1 of the Convention on the Elimination of Discrimination against Women, "discrimination against women" is defined as any distinction, exclusion or restriction made on the basis of sex "which has the effect … of impairing or nullifying the recognition, enjoyment or exercise by women … on a basis of equality of men and women, of human rights and fundamental freedoms." A system that produces a discriminatory effect by social practice or custom (a system that has the effect of preserving and fomenting discrimination) falls under "discrimination against women" referred to in Article 1 of the same Convention. Article 2 of the same Convention provides that "States Parties … agree to pursue by all appropriate means and without delay a policy of eliminating discrimination against women" (main paragraph) and undertake "to take all appropriate measures, including legislation, to modify or abolish existing laws, regulations, customs and practices which constitute discrimination against women" for that purpose ((f) of the same Article). In light of the aforementioned definition in Article 1 of the same Convention, Article 16, paragraph (1) of the same Convention provides that States Parties "shall take all appropriate measures to eliminate discrimination against women in all matters relating to marriage and family relations and in particular shall ensure the following, on a basis of equality of men and women" (main paragraph) and cites "the same personal rights as husband and wife" ((g) of the same paragraph) as an example and clearly specifies the "right to choose a family name" as an example of those personal rights.

(E) In July 2003, the Committee on the Elimination of Discrimination against Women pointed out to the Japanese government that the related provisions of the Civil Code of Japan stipulating the same surname system fall under a "system that has the effect of preserving and fomenting discrimination" under the Convention on the Elimination of Discrimination against Women in that they force a husband and wife to use the same surname and do not grant the "right to choose a family name." Since then, the same Committee has repeatedly requested Japan to rectify this system in accordance with the same Convention. The Japanese government has explained that it has a policy to make a legal amendment to deal with the problem pointed out by the Committee on the Elimination of Discrimination against Women (legal amendment of Article 750 of the Civil Code) without disputing this interpretation made by the same Committee. However, the legislative organ, the Diet, has continuously failed to take measures to make such legal amendment for a long period of time.

(F) As already pointed out in 1.(4)B. above, the same surname system is a legal system that creates a situation where a husband and wife cannot equally enjoy their personal interests in their native names, which are their personal rights, due to marriage, and it is obvious that the same surname system is not a system in which a husband and wife equally have the right to choose a surname, respectively. On the other hand, the Convention on the Elimination of Discrimination against Women has a domestic effect in Japan. Article 16, paragraph (1) of the same Convention provides for the obligations of States Parties by a legally binding text, and (g) of the same paragraph provides for the States Parties' obligation to take all appropriate measures to ensure the same personal rights as husband and wife and also clearly specifies that said personal rights include the "right to choose a family name." A legal system in which the personal right to choose a surname name as required in (g) of the same paragraph is not granted to a husband and wife, in other words, a legal system like the same surname system in Japan that obliges a husband and wife to use the same surname at the time of marriage, does not exist in other countries. In this regard, the same Convention, to which the number of States Parties had already exceeded 180 at the time of the Disposition, is considered to have made a significant contribution. In this manner, it has become an international trend to grant the right to choose a surname to both a husband and wife as a personal right just because the obligation to ensure the equality and the same personal rights of a husband and wife, which are provided as reasons for requiring said right in (g) of the same paragraph (specifically, the right to choose a surname), is based on internationally universal principles, that is, respect for human rights and the principle of equality, on which Article 13, Article 14, paragraph (1), and Article 24, paragraph (2) of the Constitution of Japan are also based.

(G) Within such context, the legislative organ, the Diet, has not amended Article 750 of the Civil Code for about a long period of 15 years from 2003, in which a problem was first pointed out to Japan regarding the same surname system by the Committee on the Elimination of Discrimination against Women, until the time when the Disposition was made. In 2016, after the 2015 Grand Bench Judgment, the Committee on the Elimination of Discrimination against Women made the third formal recommendation requiring Japan to perform the relevant obligation (the previous recommendation was made in 2003). These facts are inevitably considered to indicate that, for the obligation under the Convention on the Elimination of Discrimination against Women pertaining to a clearly specified measure to amend the same Article to achieve a system that grants the right to choose a surname to a husband and wife as the same personal right, a reasonable period of time that is considered necessary to take that measure from a common sense standpoint has passed. The same facts are also considered to indicate that at the time of the Disposition, the Diet, which is the pivotal national government organ of a State Party, Japan, had reached the condition where it cannot be considered to be pursuing the implementation of such measure without delay despite existence of the agreement referred to in Article 2 of the same Convention.

(H) Based on the aforementioned fact, that is, the fact that Japan agreed to pursue the implementation of a measure to make a legal amendment concerning the same surname system without delay in order to grant the equal right to choose a surname to a husband and wife under Article 16, paragraph (1), (g) of the Convention on the Elimination of Discrimination against Women (Article 2, (f) of the same Convention) but the State's legislative organ, the Diet, had reached the condition where it cannot be considered to be pursuing the implementation of that measure without delay, it is strongly presumed that the same surname system is not a system established from the standpoint of individual dignity and the essential equality of the sexes as referred to in Article 24, paragraph (2) of the Constitution. The reasons therefor are as follows: [i] it is clear from the context of Article 16, paragraph (1) of the same Convention that Japan was required to take a measure to make a legal amendment concerning the same surname system under the same paragraph because the same surname system is a system that goes against equality of a husband and wife in marriage and fails to ensure the personal rights of a husband and wife, respectively; [ii] equality of a husband and wife and ensuring of the personal rights of a husband and wife referred to in the same paragraph and the principles of individual dignity and the essential equality of the sexes that are indicated as a requirement or guideline that defines the limits to the legislative discretion in Article 24, paragraph (2) of the Constitution can be considered to have the same purport in terms of the underlying essence thereof, that is, respect for human rights and the principle of equality, as mentioned in (F) above. In other words, if the same surname system is a system established from the perspective of individual dignity and the essential equality of the sexes referred to in Article 24, paragraph (2) of the Constitution, the Japanese government should be able to make a counterargument that the same surname system is not considered to lack the equality of a husband and wife and the guarantee of the personal rights of a husband and wife. Therefore, it is hard to consider that the reason mentioned in [i] is applicable to the same surname system. However, in fact, based on what we can see from the materials that were made public, the Japanese government does not appear to have made such counterargument to the Committee on the Elimination of Discrimination against Women. In addition, even in 2016, the Japanese government received the third formal recommendation concerning the fact that Japan had yet to implement a measure to make a legal amendment concerning the same surname system, from the Committee on the Elimination of Discrimination against Women on the grounds that the reason mentioned in [i] is still applicable to the same surname system. In light of [ii] above, based on this fact, it is strongly presumed that at the time of the same recommendation, not only the reason mentioned in [i] was applicable to the same surname system but the same surname system was also not a system that meets the requirement of individual dignity and the essential equality of the sexes.

(I) The equality of a husband and wife and the guarantee of the personal rights of a husband and wife as referred to in Article 16, paragraph (1), (g) of the Convention on the Elimination of Discrimination against Women are considered to have the same effect as the principles of individual dignity and the essential equality of the sexes referred to in Article 24, paragraph (2) of the Constitution, as mentioned in (H) above. This idea just means that the Convention (international law) and the Constitution (domestic law) differ in the dimension but that the principles on which they are based are recognized to have mutually common universality. There is no reason for doubting this point, taking into account that the Constitution of Japan adopted internationally universal principles, that is, respect for human rights and the principle of equality. Then, even if the third formal recommendation pertaining to Article 16, paragraph (1), (g) of the same Convention that was made in 2016 was just to point out that the same surname system goes against such principles under the same Convention, it can also be considered to have been a mirror of the fact that the same surname system was also against the principles referred to in Article 24, paragraph (2) of the Constitution, that is, individual dignity and the essential equality of the sexes, which are considered to define the limits to the Diet's legislative discretion, at the time of the same recommendation. As long as this is true, in light of the fact that relevant legal amendment was not made at all during the period from the third formal recommendation to the Disposition, the fact of having received the third formal recommendation in 2016 itself becomes one of the strong grounds for supporting the idea that the same surname system was unreasonable in light of the requirement of individual dignity and the essential equality of the sexes and was beyond the scope of the Diet's legislative discretion at the time of the Disposition. It also becomes one of the reasons for determining that the same surname system is in violation of Article 24, paragraph (2) of the Constitution. The court should take this fact into consideration in making a determination on this case in light of the fact that the Convention on the Elimination of Discrimination against Women is legally binding to States Parties.

3. Concerning the point that the court should order acceptance of the Written Notification of Marriage

(1) In this case, the court of first instance rendered a ruling to dismiss without prejudice an appeal to seek a ruling to order acceptance of the Written Notification of Marriage against the Disposition. The court of prior instance rendered a decision to dismiss with prejudice on merits an immediate appeal, and a special appeal was filed against this decision. In the case where the court accepts an appeal against a disposition of non-acceptance of a written notification of marriage, it would not render a ruling to rescind the disposition of non-acceptance but would render a ruling in the form of "ordering acceptance of the written notification of marriage on the date of notification." If parts of the Provisions forcing a husband and wife to use the same surname and obliging them to make an entry of a single surname in a written notification of marriage are determined to be unconstitutional and invalid as mentioned in 1. and 2. above, the Disposition becomes an illegal disposition that is not supported by any provisions. As long as other requirements for marriage are satisfied, the municipal mayor does not have the discretion to leave the Disposition as it is. It is thus also considered that the court should render a ruling to order the municipal mayor to accept the Written Notification of Marriage on the date of the notification in the same manner as general rulings that are rendered in the case where a disposition of non-acceptance of a written notification of marriage is found illegal. Incidentally, Article 34, paragraph (2) of the Family Register Act provides that "the mayor of a municipality may not receive a written notification in which such matters as he/she finds to be particularly important have not been entered." However, as long as the provisions that force a husband and wife to use the same name and oblige them to make an entry of a single surname in a written notification of marriage are unconstitutional and invalid, the fact that the appellants did not decide a single surname that they will adopt and enter it in the Written Notification of Marriage does not become a ground for non-acceptance under the same paragraph.

(2) Then, formation of marriage by acceptance of a written notification of marriage and subsequent handling, such as entry in a family register, are conceptually distinguishable. If marriage is formed, various legal effects, such as the obligations to live together and to provide mutual cooperation and assistance as a husband and wife and succession, occur. In the case of a breakup, a married couple is required to take divorce procedures. Even if a written notification of marriage in which separate surnames are entered for a husband and wife is accepted, how to create and make entries in a family register (whether or not such husband and wife are entered in the same family register; if such husband and wife are entered in the same family register, who is entered at the head of the family register) might have to be kept pending until a legal amendment is made. Therefore, the parties might become unable to request the issuance of a transcript of a family register to certify the fact of their marriage. However, in such case, the parties are probably able to request the issuance of a certificate of acceptance of a written notification of marriage pursuant to the provisions of Article 48, paragraph (1) of the Family Register Act.

(3) Moreover, for the period from a legal amendment until its enforcement, there will be the problem of impossibility of legally deciding the surname of a child born to a husband and wife who decided to adopt separate surnames at the time of marriage. However, regarding this problem, if it is necessary to certify the birth of such child, his/her parents are probably able to request the issuance of a certificate of acceptance of a written notification of birth pursuant to the provisions of Article 48, paragraph (1) of the Family Register Act. Even if there is the problem of impossibility of legally deciding a surname of a child born, it cannot be said that it is possible to refuse to accept a written notification of marriage for that reason without promptly making a legal amendment to resolve the problem.

(4) Needless to say, if the Diet comes to have the obligation to make a legal amendment to the Provisions in response to the determination of this Court that the Provisions are unconstitutional, it is necessary to promptly implement the legislative process, including not only acceptance of marriage in which a husband and wife adopt separate surnames but also a legal amendment concerning related matters, such as a child's surname and the handling of a family register of such husband and wife. However, as already mentioned, there is no foreign country that adopts a system obliging a husband and wife to use the same surname. Therefore, there should be many legal systems that accept the use of separate surnames by a husband and wife, in addition to the use of the same surname by a husband and wife, in the world. In 1996, the Ministry of Justice conducted necessary surveys on foreign systems, and the Legislative Council completed deliberations and made a report of the outline of a bill indicating the direction of amendment to the same surname system. Taking these into account, it is hard to consider that the Diet cannot promptly implement a legal amendment concerning related matters, including the method of deciding a child's surname, in making an amendment to accept marriage of persons who wish to use separate surnames after marriage. The Diet is required to amend the Provisions to ensure that all citizens can make a decision to marry freely and equally and to realize legal provisions enacted from the standpoint of individual dignity and the essential equality of the sexes, and it is also required to promptly amend related provisions in order to secure the interests of children and ensure appropriate notarial function with regard to a husband and wife who wish to use separate surnames.

The dissenting opinion stated by Justice KUSANO Koichi is as follows.

Contrary to the majority opinion, I consider that the Provisions should inevitably be judged to be in violation of Article 24 of the Constitution, and therefore that the decision in prior instance should be quashed and it should be ordered that the appellants' notification of marriage be accepted. The reasons for my opinion are as follows.

1. It is appropriate to construe that when the legal provision that prescribes a legal system concerning marriage and the family does not violate Article 13 or Article 14, paragraph (1) of the Constitution, determination as to whether or not said provision can also be accepted as being in compliance with Article 24 of the Constitution should be made by examining the purpose of the legal system and the influence that may be derived from adopting the legal system, and by considering whether or not the provision in question should inevitably be deemed to be unreasonable in light of the requirement of individual dignity and the essential equality of the sexes and be beyond the scope of the Diet's legislative discretion (2015 Grand Bench Judgment).

In determining whether the Provisions that stipulate the same surname system can be deemed to be unreasonable to a level beyond the scope of the Diet's legislative discretion as mentioned above, I think it is helpful to compare the benefits for citizens that would be increased, and the benefits for citizens that would be reduced, by introducing the optional separate surname system, which is recommended as the most possible substitute for the current same surname system ("benefits" mentioned here means the interests to be enjoyed by citizens as individuals, and it does not include the "interests of society as a whole" or the "interests of a specific community or organization" apart from individuals). In light of the fact that Article 24, paragraph (2) of the Constitution requires that systems concerning marriage and the family be based on "individual dignity," an approach to consider the issue by excluding values that cannot provide benefits for citizens from the scope of consideration may be suited to determining the applicability of that Article, and, consideration from such viewpoint may allow more possibilities to verify the validity of arguments by using the rules of logic or rules of thumb (although it is ultimately inevitable to make a certain value judgment).

Having said that, except when the types of the benefits under comparison are the same or these benefits can be the subject of transaction between the related parties, it is necessary to make a certain value judgment in order to rank benefits in terms of size, and hence, the legislative discretion of the Diet, which consists of representatives of citizens, should be respected in comparing benefits. However, it is obvious that the benefits that would be increased by the introduction of the optional separate surname system are far greater than the benefits that would be reduced by the introduction of this system, and none of the benefits that would be reduced can be regarded as human rights or equivalent interests. Given these points, it must be said that deciding not to introduce this system is an act that ignores individual dignity excessively and that such act is unreasonable to a level beyond the scope of the Diet's legislative discretion mentioned above. Therefore, the Provisions should be judged to be in violation of Article 24 of the Constitution.

A marriage system incorporates rules that form the backbone of ethics in society (for example, rules prohibiting bigamy and rules prohibiting marriage between close relatives by blood), and it may be difficult to ascertain the entirety of the interests brought to citizens by these rules merely by microscopically or analytically examining the influence of the rules on the benefits for citizens. However, apart from the situation under the prewar "family" system, it may be clearly inappropriate, under the current Constitution and the current family system that deny the prewar system, to regard the Provisions that stipulate the same surname system as forming the backbone of ethics in society (moreover, if the same surname system has a function to increase the benefits for all members of society through relationships of mutual dependence based on people's behavior and mindset, there may be the same concern as above about methodology for comparing benefits, but the existence of such function of the system has not yet been argued specifically to the level where it can be verified).

2. From the standpoint mentioned above, I will analyze and compare the benefits for citizens that would be increased, and the benefits for citizens that would be reduced, by introducing the optional separate surname system.

(1) Benefits for citizens that would be increased by introducing the optional separate surname system

A person's surname, in combination with the person's given name, is an important element for identifying the person, and there may be many people in society who have a strong attachment to their surnames that they have become accustomed to throughout their lives. For these people, being forced to change their surnames even for the purpose of marriage would considerably reduce their benefits. In addition, it is obvious that if a person is hindered from continuing to use one's surname, this would reduce the person's benefits in leading a life in society, and this point has become an increasingly serious problem today when dual-career couples and delayed marriage become more popular than ever. Although the situations where people can continue to use their pre-marriage surname in social life even after changing their surname in the family register have been increasing, there are necessarily limitations to the opportunities for them to use their pre-marriage surname. Accordingly, they are compelled to use two surnames in different situations or use both surnames on the same occasion. This is in itself burdensome and it also results in diluting one's identity in their name, which would inevitably reduce their benefits.

In short, the same surname system would considerably reduce the benefits for a party to marriage who changes his/her surname upon marriage, and the optional separate surname system, which can solve this problem, would increase the benefits for citizens certainly and remarkably.

One of the aspects of the reduction in benefits experienced by a party to marriage who changes his/her surname under the same surname system may be that it is difficult to secure the "interest in keeping the fact of marriage secret." I will explain this point in detail. The fact as to whether one is married or not is important personal information along with the age, place of birth, and academic background, and for this reason, if some people wish to keep the fact of their marriage secret, their request is worth respecting. Having said that, it is also true that someone would find it helpful for increasing benefits to know of the marital relationships of people who wish to keep the fact of their marriage secret (for example, for the company management, it is beneficial from the perspective of personnel management to know whether their employees are married or not). However, if it is determined that there is interest in keeping the fact of marriage secret and such interest is worth respecting, a person that needs information concerning other persons' marriage should request the other persons to disclose information concerning their marriage in exchange for certain incentives (in such case, a party to marriage who considers that the incentives given thereto is greater in value than the disadvantage of disclosing the fact of his/her marriage would disclose information concerning marriage, whereas the person in need of such information that considers that the benefit of knowing the fact of the other person's marriage is greater in value than possible incentives given thereby would actually offer such incentives). A negotiation regarding the disclosure of information could incur some transaction costs, but even in consideration of such costs, it may be obvious that if the decision to disclose information or not is left to a negotiation between the parties (this is possible under the optional separate surname system), the sum of the benefits for all related parties would be greater than that under a system that could result in disclosing the fact of marriage without compensation against the will of the party to marriage (the same surname system can be regarded as such system).

(2) Benefits for citizens that would be reduced by introducing the optional separate surname system

A. Influence on the benefits for parties to marriage

Parties to marriage are likely to enjoy more benefits by adopting the same surname and thereby sharing the sense of unity as a family. Therefore, even if the optional separate surname system is introduced, not a few married couples would choose the same surname, and only those who consider that the reduction in benefits that are pointed out in (1) above would be greater than the increase in benefits brought about by adopting the same surname would choose separate surnames. In short, the introduction of the optional separate surname system would possibly increase but could never reduce the sum of the benefits for both parties to marriage (since the parties to marriage can share various benefits with each other, as the sum of the benefits for both parties to marriage is increased, the benefits for each party to marriage are also likely to be increased.)

B. Influence on the benefits for a child

The issue that should to be considered here is the benefits for a child born to the married couple who have chosen to adopt different surnames because, although a child is a legal subject who has personality separate from the parents, the child is destined to accept the consequence arising from the parents' choice of separate surnames, without consenting to it. It is an undeniable fact that if one of the parents has a surname different from the child's surname, this would reduce benefits for the child in some forms, such as reducing the sense of unity as a family.

However, most of the reduction in benefits brought about to the child due to the parents choosing separate surnames is premised on the fact that it is a standard practice in society for the married couple to adopt the same surname. Therefore, if the optional separate surname system is introduced and many married couples choose separate surnames, the influence of the parents' choice of separate surnames on their child would be reduced significantly. Furthermore, under the current law, the parents have a broad discretion to decide matters that could affect the benefits for the child (e.g., rearing and taking custody of the child and education for the child), and even if, in some cases, the parents' pursuit of their own legitimate benefits inevitably hinders the maximization of the child's benefits, such conduct of the parents is not generally regarded as going beyond the bounds of their discretion unless the child's benefits that cannot be realized can be deemed to be the child's human rights or equivalent interests. In light of integrity with this, when persons who are to marry decide whether to choose separate surnames, it is appropriate to leave it to the discretion of the parents (the married couple) how to take into consideration the married couple's own benefits and their child's benefits, and even if the married couple's choice of separate surnames hinders the maximization of the child's benefits, it should be said that this cannot be the reason to prevent the married couple from pursuing their own benefits.

C. Influence on the benefits for relatives

If a married couple chooses the same surname, the relatives of the party to marriage who does not change his/her surname can reinforce the sense of unity with the other party to marriage by sharing the surname with that party. However, the choice of the same surname functions to reduce the sense of unity that the party to marriage who changes his/her surname has fostered with the party's relatives, and in this respect, it cannot be said by any means that the introduction of the optional separate surname system will reduce the sum of the benefits for the relatives of both parties to marriage.

Having said that, it is still an unchanging fact in modern society that some relatives of either party to marriage give living support to the other party to marriage (such relatives are hereinafter referred to as "supporting relatives"). It is likely that supporting relatives would strongly desire that the other party to marriage change his/her surname in order to reinforce the sense of unity between them and that party, and at the same time, if only one party to marriage has such supporting relatives, the relatives of the other party to marriage would feel that it is inevitable for that party to change his/her surname. Therefore, only in such case, it can be said that if the parties to marriage choose the same surname by adopting the surname of the supporting relatives, the sum of the benefits for the relatives of both parties to marriage is likely to be greater than when they choose separate surnames.

However, the supporting relatives are in the position where they can communicate to the other party to marriage their wish to have that party change his/her surname by informing that party of the details of the support they are ready to give, and if that party, even after being so notified and informed, still does not agree to change his/her surname, this may suggest that said party considers that he/she would suffer excessive reduction in benefits from changing his/her surname, even after fully understanding the supporting relatives' wish to have said party change his/her surname and fully taking into consideration the support the relatives would give. As marriage is an act that two persons carry out by betting their lives on each other, the benefits for the parties to marriage should be given preference to the benefits for their relatives in connection with the issue of whether either of the parties changes his/her surname, and even if the benefits for the supporting relatives are reduced through the introduction of the optional separate surname system in the abovementioned case, this cannot be considered to be the reason for hindering the fulfillment of the benefits for the parties to marriage because of that.

D. Same surname system as custom

If there are people, other than those discussed in A. to C. above, whose benefits would be reduced if the parties to marriage choose separate surnames, such people may be those who wish to preserve the same surname system as a "beautiful custom" of Japan, as it has been maintained for a long period of time.

However, even when the optional separate surname system is introduced, this would not necessarily result in the extinction of the tradition of a married couple adopting the same surname. If many Japanese citizens think that it is a beautiful tradition of Japan for a married couple to adopt the same name, this tradition is likely to survive in the future. In addition, there are many traditional cultures in Japan that people want to preserve (these cultures can be described as having a strong positive externality) (e.g., the landscape of satoyama (mountainous areas located around villages), manner of speaking with a dialectal accent, lifestyle full of compassion for people in shitamachi (traditional downtown areas), chinju no mori (forests around shrines), and seasonable festivals and events). How these traditional cultures will survive in the future should ultimately be left to the consequences resulting from the dynamism of society (such dynamism of course includes movements to protect such traditional cultures), and it can hardly be said that forcing these traditional cultures to survive by the power of law conforms to the constitutional order of Japan. The same surname system may possibly be regarded as one of such traditional cultures (moreover, focusing on the positive externality of the same surname system toward people other than the related parties, the benefit of this system seems to be unclear when compared to the traditional cultures exemplified above). Therefore, although it cannot be said that there is absolutely no possibility that the same surname system would become extinct as a result of the introduction of the optional separate surname system, even if there is the possibility that the extinction may reduce mental benefits for some people, this cannot be considered to be the reason for hindering the fulfillment of the benefits for the parties to marriage because of that.

E. Influence on the family register system

For the smooth enforcement of the optional separate surname system, it is necessary to amend the provisions of the Family Register Act, and the content of such amendment is partially left to be discussed in further detail from the perspective of legal technique. However, even if the amendment is actually made upon the introduction of the optional separate surname system, this would not interfere with various functions that the family register system performs for the benefits for citizens (e.g., the function to register and notarize the family relationships among relatives, and the function to register and notarize the Japanese nationality).

3. For the reasons stated above, it is obvious that the benefits that would be increased by the introduction of the optional separate surname system are far greater than the benefits that would be reduced by the introduction of this system, and none of the benefits that would be reduced can be regarded as human rights or equivalent interests. Given these points, it must be said that deciding not to introduce this system is an act that ignores individual dignity excessively and that such act is unreasonable to a level beyond the scope of the Diet's legislative discretion. Therefore, the Provisions should be judged to be in violation of Article 24 of the Constitution.

Justice OTANI Naoto

Justice IKEGAMI Masayuki

Justice KOIKE Hiroshi

Justice KIZAWA Katsuyuki

Justice KANNO Hiroyuki

Justice YAMAGUCHI Atsushi

Justice TOKURA Saburo

Justice MIYAZAKI Yuko

Justice MIYAMA Takuya

Justice MIURA Mamoru

Justice KUSANO Koichi

Justice UGA Katsuya

Justice HAYASHI Michiharu

Justice OKAMURA Kazumi

Justice NAGAMINE Yasumasa