Marriage in Japan: What are the Legal Requirements and Consequences?

Japanese Attorney at Law - Bengoshi L.L.

• 11 min read

Marriage, a cornerstone of society globally, carries profound legal significance in Japan. Beyond its social and cultural dimensions, entering into a marital union under Japanese law establishes a distinct legal status, conferring a host of rights and obligations upon the spouses. Understanding the specific requirements for forming a valid marriage and the extensive legal consequences that ensue is crucial for anyone navigating family law in Japan, including international individuals and legal professionals advising them. This article explores the essential legal framework governing marriage in Japan, from its formation to its wide-ranging effects.

Japanese law adopts a system of "legal marriage" (hōritsukon), meaning that for a marriage to be legally recognized and to produce legal effects, it must comply with specific substantive and formal requirements stipulated in the Civil Code and the Family Register Act (Koseki Hō). Unlike some jurisdictions that recognize common-law marriages or de facto unions as conferring similar rights to formal marriage, Japan draws a clearer line, though "de facto marriages" (naien) do receive certain protections, which are distinct from those of legal marriage.

A. The Essential Element: Marital Intent (婚姻意思 - Kon'in Ishi)

The foremost substantive requirement for a valid marriage is the genuine and mutual intent of both parties to marry. The Japanese Civil Code (Article 742, Paragraph 1) states that a marriage is void if there is no intent to marry between the parties due to a mistake in identity or other reasons. This "marital intent" is generally understood as the intention to create a genuine spousal relationship, encompassing cohabitation, cooperation, and mutual support as socially understood.

Nuances of Marital Intent: Substantive vs. Formal

Japanese legal scholarship has long debated the precise nature of this intent. The prevailing view, often termed the "substantive intent theory" (jisshitsu-teki ishi-setsu), emphasizes that parties must intend to establish a relationship with the social and legal substance of a marriage. This means a shared life, mutual fidelity, and the assumption of spousal responsibilities.

This contrasts with a purely "formal intent theory" (keishiki-teki ishi-setsu), which might suggest that merely intending to file the marriage notification would suffice. However, Japanese courts have generally sided with the substantive view. For example, a marriage entered into solely for a collateral purpose, without the genuine intention to live as husband and wife (a "sham marriage"), can be declared void. A significant Supreme Court decision on October 31, 1969 (最判昭和44年10月31日民集23巻10号1894頁) dealt with a case where parties registered a marriage solely to legitimize a child, with an immediate plan to divorce. The Court held that if the "intention to establish a relationship recognized in social common sense as that of husband and wife" was absent, the marriage was void.

Timing of Intent

Generally, marital intent must exist at the time the marriage notification is filed and accepted. This can become complex if, for instance, one party loses mental capacity or dies between signing the notification form and its official acceptance. The Supreme Court, in a decision on April 3, 1969 (最判昭和44年4月3日民集23巻4号709頁), held that if a marriage notification was prepared based on the parties' clear intent and a de facto marital relationship existed, the marriage could be valid even if one party was unconscious when the notification was accepted, provided there was no change of intent before incapacitation. This indicates a somewhat flexible approach aimed at upholding genuine marital intentions where a factual spousal relationship was already in place.

B. Substantive Impediments to Marriage (婚姻障害事由 - Kon'in Shōgai Jiyū)

Beyond marital intent, the Civil Code lists several impediments that can prevent a valid marriage:

  1. Marriageable Age (婚姻適齢 - Kon'in Tekirei) (Article 731): Currently, males must be 18 years old and females 16 years old to marry. There have been ongoing discussions and legislative proposals to equalize the marriageable age to 18 for both sexes, reflecting evolving societal views and international standards on child rights.
  2. Prohibition of Bigamy (重婚でないこと - Jūkon de nai koto) (Article 732): A person who is already legally married cannot enter into another marriage. This upholds the principle of monogamy.
  3. Waiting Period for Remarriage (for women) (待婚期間 - Taikon Kikan) (Article 733): Women cannot remarry until 100 days have passed since the dissolution or annulment of their previous marriage. The historical rationale was to avoid confusion regarding the paternity of a child born shortly after remarriage. This period has been shortened from the original six months following criticism and considerations of gender equality, as well as advancements in paternity testing. The waiting period does not apply if the woman was pregnant before the dissolution of the previous marriage and gives birth, or if there is medical certification that she is not pregnant at the time of dissolution or has not been pregnant since.
  4. Prohibition of Consanguineous Marriages (近親婚でないこと - Kinshinkon de nai koto) (Articles 734-736): Marriage is prohibited between lineal blood relatives (e.g., parent-child, grandparent-grandchild), between collateral blood relatives within the third degree of kinship (e.g., siblings, uncle-niece, aunt-nephew), and between lineal relatives by affinity (e.g., a person and their spouse's parent). These prohibitions aim to prevent genetic issues and uphold societal moral standards.
  5. Parental Consent for Minors (未成年者は父母の同意があること - Miseinensha wa fubo no dōi ga aru koto) (Article 737): A minor (under 18, the age of majority effective April 1, 2022; previously 20) who has reached marriageable age still requires the consent of at least one parent to marry. If one parent objects, the consent of the other is sufficient. If both parents are deceased or unable to give consent, the minor's legal guardian's consent is needed. However, the lack of this consent does not render the marriage void, but rather voidable, and the right to annul is limited.
  6. Requirement of Opposite Sexes: While not explicitly stated as a numbered impediment, the Japanese Civil Code and family registration system are structured on the premise that marriage is a union between a man and a woman. The provisions concerning surnames (requiring a couple to choose one surname) and the roles within traditional family structures implicitly support this. There is no legal framework for same-sex marriage in Japan, although societal discussions and some lower court rulings in recent years have highlighted calls for its recognition and the potential for unconstitutionality in denying it.

C. The Indispensable Formality: Notification (Todokede) (Article 739)

The crucial formal requirement for a marriage to be legally effective in Japan is its notification (todokede) and acceptance by the municipal office, leading to its recording in the family register (koseki). Article 739, Paragraph 1 of the Civil Code states: "A marriage becomes effective upon notification thereof pursuant to the provisions of the Family Register Act."

This notification is not merely evidentiary; it is constitutive of the legal marriage. Without this formal registration, even if a couple has a wedding ceremony, cohabits, and is socially recognized as married, they are generally considered to be in a "de facto marriage" (naien), which has different and more limited legal consequences than a registered marriage. The notification must be signed by both parties and at least two adult witnesses, and then submitted to the relevant municipal office.

Once a marriage is validly formed, a wide array of legal effects arise, fundamentally altering the personal and property relations of the spouses and their relationship with society and any children born to the union.

A. Personal Effects (人格的効果 - Jinkakuteki Kōka)

  1. The Triad of Spousal Duties (Article 752): Cohabitation, Cooperation, and Support.
    • Cohabitation (同居 - Dōkyo): Spouses have a mutual duty to live together. However, courts may recognize justifiable reasons for separate living, such as work assignments in different locations, and will not typically enforce cohabitation against the will of a spouse. The Supreme Court has shown that this duty is subject to the specific circumstances of the couple and that agreements to live separately, while not voiding the marriage, may be considered in disputes.
    • Cooperation (協力 - Kyōryoku): This is a general duty for spouses to cooperate in maintaining their marital life. Its specific content is broad and depends on the circumstances.
    • Support (扶助 - Fujo): Spouses have a duty to support each other financially. This is often characterized as a "duty to maintain a similar standard of living" (seikatsu hoji gimu), which is considered a higher level of support than the general duty of support among other relatives. This duty is closely linked to the sharing of marital expenses.
  2. Duty of Fidelity (貞操義務 - Teisō Gimu)
    While not explicitly stated as a standalone duty in a single article, the duty of fidelity is firmly implied in Japanese family law, primarily through Article 770, Paragraph 1, Item 1, which lists spousal infidelity (futei kōi) as a ground for judicial divorce.
    • Consequences of Breach: A breach of this duty can lead to divorce and may also give rise to a claim for damages (慰謝料 - isharyō) for emotional distress, not only against the unfaithful spouse but also against the third party involved in the adulterous relationship. The Supreme Court decision of March 30, 1979 (最判昭和54年3月30日民集33巻2号303頁) affirmed the right of a spouse to claim damages from their spouse's adulterous partner.
    • Adultery After Marital Breakdown: The legal implications of infidelity can change if the marital relationship has already irretrievably broken down. The Supreme Court decision of March 26, 1996 (最判平成8年3月26日民集50巻4号993頁) held that if a marriage has broken down to the extent that the purpose of marital cohabitation is lost, a sexual relationship with a third party by one spouse may not constitute a tort against the other spouse, as the legally protected interest of peaceful marital cohabitation no longer exists.

B. Property Effects (財産上の効果 - Zaisan-jō no Kōka)

Marriage significantly impacts the property rights and obligations of the spouses.

  1. Marital Property Regimes (夫婦財産制 - Fūfu Zaisan-sei)
    Japanese law provides for both a statutory marital property regime and the possibility of a contractual regime (Article 755).
    • Contractual Regime (夫婦財産契約 - Fūfu Zaisan Keiyaku): Spouses can, before marriage notification, enter into a contract regarding their property. However, such contracts are exceedingly rare in Japan, partly due to lack of social custom and procedural complexities, including the need for registration to be effective against third parties (Article 756).
    • Statutory Regime (法定財産制 - Hōtei Fūfu Zaisan-sei): In the absence of a marital property contract, the statutory regime applies. Its key components are:
      • Separate Property Principle (夫婦別産制 - Fūfu Bessan-sei) (Article 762): This is the fundamental principle. Property owned by one spouse before marriage, and property acquired in that spouse's own name during the marriage, is considered their separate property (特有財産 - tokuyū zaisan). Property whose ownership is unclear is presumed to be co-owned. Academic theories, such as the "potential joint ownership theory" (senzai-teki kyōyū-sei-ron), have attempted to interpret this principle in a way that gives more recognition to a non-earning spouse's contributions, particularly in divorce settlements. The Supreme Court decision of September 6, 1961 (最(大)判昭和36年9月6日民集15巻8号2047頁) upheld the constitutionality of the separate property system against a challenge based on alleged inequality.
      • Sharing of Marital Expenses (婚姻費用の分担 - Kon'in Hiyō no Buntan) (Article 760): Spouses are to share the expenses arising from the marriage, taking into account their assets, income, and all other circumstances. This is often litigated in cases of separation or impending divorce.
      • Joint Liability for Daily Household Debts (日常家事債務の連帯責任 - Nichijō Kaji Saimu no Rentai Sekinin) (Article 761): If one spouse incurs debts in connection with daily household matters, the other spouse is jointly and severally liable, unless prior notice was given to the third party that the other spouse would not assume such liability. The scope of "daily household matters" depends on the couple's social standing, lifestyle, and assets.
  2. Right to Cancel Inter-Spousal Contracts (夫婦間の契約取消権 - Fūfu-kan no Keiyaku Torikeshi-ken) (Article 754)
    Contracts made between spouses can be cancelled by either spouse at any time during the marriage, provided it does not prejudice the rights of third parties. The traditional rationale for this rule included protecting a spouse from undue influence or emotional pressure. However, this right has been significantly curtailed by judicial interpretation. Courts, including the Supreme Court (e.g., decision of March 6, 1958 (最判昭和33年3月6日民集12巻3号414頁), and decision of February 2, 1967 (最判昭和42年2月2日民集21巻1号88頁)), have held that this right to cancel cannot be exercised if the marital relationship has effectively broken down, as the original purpose of the rule (protecting marital harmony or a vulnerable spouse within an ongoing relationship) no longer applies. There have been strong calls for the legislative abolition of this provision, and it was included in a 1996 outline for Civil Code reform proposals, though these reforms have not yet been enacted.

C. Effects on Status and Relation to Third Parties

  1. Legitimation of Children (子の嫡出化 - Ko no Chakushutsu-ka) (Article 772): A child conceived by a wife during marriage is presumed to be the child of her husband. Marriage thus confers legitimate status upon children born within it.
  2. Common Surname (氏の共通 - Uji no Kyōtsū) (Article 750): Upon marriage, a couple must choose to adopt the surname of either the husband or the wife. This is a mandatory requirement. While gender-neutral in wording, over 95% of couples choose the husband's surname. This system has been a subject of intense debate, with significant public and legal discussion around the introduction of a "selective separate surname system" (sentaku-teki fūfu bessei-sei), which would allow spouses to retain their pre-marital surnames. A 1996 Ministry of Justice advisory council proposed this change, but it has faced considerable opposition and has not yet been legislated, highlighting a tension between traditional family values and individual identity rights.
  3. Creation of Affinity (姻族関係の発生 - Inzoku Kankei no Hassei) (Article 725): Marriage creates relationships by affinity between one spouse and the blood relatives of the other spouse.
  4. Attainment of Majority by Marriage (成年擬制 - Seinen Gisei) (Article 753): If a minor marries, they are deemed to have attained the age of majority for the purposes of private law. This means they can enter into contracts and conduct other legal acts as an adult. This does not, however, change their status for public law purposes, such as voting age or the legal age for smoking and drinking.

III. When Things Go Wrong: Nullity and Annulment of Marriage

Defects in the formation of a marriage can lead to its being either void (無効 - mukō) or voidable (annullable) (取消 - torikeshi).

A. Grounds for Nullity (婚姻の無効 - Kon'in no Mukō)

According to Article 742 of the Civil Code, a marriage is void if:

  1. There is no intent to marry on the part of one or both parties due to a mistake in identity or other reasons (e.g., a complete sham marriage entered into for a fraudulent purpose without any intent to live as spouses).
  2. The parties fail to file the marriage notification. In practice, if there is no notification, no legal marriage is formed in the first place, so this provision primarily addresses situations where a notification exists but is fundamentally flawed regarding intent.

A void marriage is treated as if it never existed from the beginning (ab initio).

B. Grounds for Annulment (婚姻の取消 - Kon'in no Torikeshi)

A marriage that is not void but suffers from certain defects is voidable, meaning it is valid until a court annuls it. Grounds for annulment include:

  1. Non-compliance with substantive requirements (Article 744): This covers marriages contracted in violation of the marriageable age, the waiting period for women, or the prohibitions against bigamy and marriage between close relatives. The right to request annulment may be limited to certain persons or be subject to time limits (e.g., an underage marriage can no longer be annulled by relatives once the party reaches marriageable age, though the party themself can do so for a short period thereafter - Article 745).
  2. Marriage by Fraud or Duress (詐欺・強迫 - Sagi・Kyōhaku) (Article 747): A spouse who married due to fraud or duress can request annulment. This right to annul is lost if three months have passed since discovering the fraud or escaping the duress, or if the party has ratified the marriage.

Unlike nullity, the annulment of a marriage generally has prospective effect; it does not retroactively invalidate the marriage (Article 748). The financial consequences of an annulled marriage, such as property division, are often handled similarly to those in a divorce (Article 749).

IV. Conclusion

Marriage under Japanese law is a formally regulated institution with clearly defined entry requirements and a comprehensive set of legal consequences. The emphasis on genuine marital intent and adherence to statutory impediments underscores the seriousness with which the legal system views the marital bond. Once formed, a marriage profoundly impacts the personal duties of the spouses, their property relations, their social identity through a shared surname, and the status of their children. While societal views on marriage evolve, particularly concerning issues like spousal surnames, the fundamental legal framework established by the Civil Code continues to govern this essential human relationship, with the Family Court playing a pivotal role in resolving disputes that arise within it. Understanding these legal parameters is essential for comprehending the Japanese approach to family and societal structure.