Japan Will Finally Repeal 300-Day Paternity Rule from 1898

Japan Will Finally Repeal 300-Day Paternity Rule from 1898

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Divorce and paternity
Picture: ペイレスイメージズ1(モデル) / PIXTA(ピクスタ)
Japan's government signals it'll scrap a Meiji era law that has put women at risk and left hundreds of kids unregistered.

On October 14, 2022, Japan’s Cabinet approved a draft of legislation aiming to repeal a longstanding rule that a child born within 300 days of divorce is legally the child of a woman’s ex-husband.

First proposed in February of this year, the bill will now appear before the National Diet in the near future. The Diet plans to address the amendment to the 300-day rule during its current session. This session opened on October 3 and will run through mid-December. 

The purpose of the amendment is to decrease the number of unregistered children (mukoseki) in Japan. Many women who do not wish to comply with the 300-day rule respond by not registering their child at all. Unregistered children frequently experience a number of difficulties in life including the inability to access healthcare or order a passport.

The amendment also serves to address Japan’s gender gap by removing the rule preventing women from remarrying within 100 days of divorcing their previous husbands.[1]

What Is the 300-Day Rule?

Middle aged couple getting divorced
Picture: Canva

A Civil Code instituted in 1898 states that a child born within 300 days of divorce is legally the child of the woman’s ex-husband. This law does not recognize the child’s actual biological parentage. It also still applies even if the woman has remarried. This is despite joint parenting post-divorce being rare in Japan.

Lawmakers likely implemented this because Japan utilizes a household registry system, rather than an individual one. Children are considered part of the father’s register, not the mother’s. However, in many instances, including cases of domestic abuse, women responded by refusing to register their children at all.

A survey of 800 unregistered residents of Japan found that nearly 600 of them cited the 300-day rule as the reason they were unregistered. Many of the unregistered individuals had no passports, could not access healthcare, and had not been able to receive public education.


Tomoshi Sakka, a prominent lawyer who argues for the rights of women and children, stated that the amendment of this archaic law would go a long way towards improving the situation for future children. In a public statement regarding the law, Sakka said of Japan’s lawmakers “They have finally realized that this law is for the children.” [2]

Narrowing Japan’s Gender Gap

A cartoon man in a suit happily ascends a staircase with ease while a woman trails behind him, saddled with a heavy bag labeled "weight"

The removal of the 300-day rule could also represent a significant step towards narrowing Japan’s very much extant gender gap. In the 2022 version of the World Economic Forum’s Gender Global Gender Gap Report, published annually in July, Japan ranked 116th out of the 146 countries surveyed. In particular, the report called out Japan as one of 32 surveyed countries that continued to place post-divorce restrictions on women but not men.

This amendment could mark another step forward for women’s marriage and divorce rights in Japan. In 2015, Tomoshi Sakka spearheaded a ruling by Japan’s Supreme Court addressing the law regarding women’s remarriage. The period of time when a woman could not remarry after divorce was shortened from six months to 100 days. With further amendment, this 100-day limit may be removed entirely.

Lawmakers are also considering a future amendment that would allow children and mothers to file paternity denial claims. Currently, only the woman’s husband or ex-husband can file a paternity denial claim.

Further Amendments May Be Coming

The subcommittee responsible for revising the amendment before presenting it to the National Diet has also suggested that the term “disciplinary rights” should be removed from the existing Civil Code. Currently, parents have the right to discipline any of their children with few to no limitations. However, the subcommittee believes that this wording has been used to justify abuse, and more restrictions should be placed on a parent’s authority over their children. [3]

Whether or not the amendment gets passed and the 300-day law removed will likely be announced at the conclusion of the current National Diet session. In the meantime, many prominent Japanese publications continue to report on the issue, while ordinary citizens have taken to social media to publicly declare support for the rule’s removal. This abolition of an archaic code from over a century ago could be a huge step forward for both women and children in Japan.


[1] Kyodo News. “Japan eyes shake-up of system for recognizing paternity after divorces.” 14 October 2022. Link.

[2] Reynolds, Isabel and Marika Katanuma. “Japan set to drop archaic paternity rule for divorced women.” The Japan Times. 15 October 2022. Link.

[3] Mainichi Shinbun. “離婚後300日以内でも「再婚夫の子」に 法制審部会、改正案了承” 1 February 2022. Link.

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Kay Benton

Kay is a longtime Japan enthusiast and former participant in the JET Program. Their favorite thing to do when traveling in Japan is visiting as many onsens as possible.

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