Case Requesting Confirmation of Obligation to Investigate Biological Parent, etc. (Reiwa 3 (Wa) 28700)

In 2021, a Japanese woman born through artificial insemination by donor (AID) filed a lawsuit with the Tokyo District Court against the State of Japan. She sought confirmation that the state has a duty to establish a system enabling her to investigate her biological father, and claimed damages for legislative inaction. She argued that her right to know her own origins is constitutionally protected. Both the Tokyo District Court (2022) and the Tokyo High Court (2023) dismissed her claims, ruling that no specific right existed under current law. The case was appealed to the Supreme Court, and in March 2025, the Grand Bench unanimously upheld the lower courts' decisions, holding that the Constitution does not compel the state to create such an investigative framework. This was the first AID origin-knowledge case to reach Japan's highest court.

The Supreme Court of Japan dismissed the appeal, upholding the lower court rulings that the state has no legal obligation to establish an investigation system. The plaintiff's claim for state compensation was also rejected.

Whether a child born through assisted reproductive technology has a constitutionally guaranteed right to know the identity of their biological father, and whether the state has a corresponding constitutional duty to legislate a system to facilitate such disclosure.

The ruling ignited widespread debate on the rights of donor-conceived individuals in Japan. It underscored the legal vacuum surrounding assisted reproduction and prompted the Diet to accelerate discussions on legislation governing donor information management, balancing the child's right to identity against donors' anonymity. Advocacy groups intensified calls for a national registry, making donor conception rights a prominent policy issue.