With regards to the estate of P, who died in July 2001, the appellees who are P's children born in wedlock filed a petition for a ruling on the division of P's estate against the appellants, who are P's children born out of wedlock. Relying on the 1995 Decision, the court of prior instance, the Tokyo High Court, determined that the Provision was not in violation of Article 14, paragraph (1) of the Constitution, and concluded that P's estate should be divided based on the respective statutory shares in inheritance of the appellees and the appellants as calculated by applying the Provision. The appellants argued that the Provision is in violation of Article 14, paragraph (1) of the Constitution and therefore void.
The SCJ [Suprene Court of Japan] (GB [Grand Bench]) quashed the decision of the Tokyo High Court by concluding that the Provision was in violation of Article 14 paragraph (1) of the Constitution as of July 2001 at the latest.
The 2013 Decision emphasized that the matters to be considered (such as tradition, social conditions and public sentiments) change with time. Therefore, the reasonableness of the rules should be subject to constant examination and scrutiny in light of the Constitution, which provides individual dignity and equality under the law.
Quotations from the court decision:
Article 14, paragraph (1) of the Constitution provides for equality under the law, and this provision should be interpreted as prohibiting any discriminatory treatment by law unless such treatment is based on reasonable grounds in relation to the nature of the matter. This is the case law established by the precedent rulings of this court.
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Even if the legal marriage system itself is entrenched in Japan, it is now impermissible, as a result of such change in the recognition, to cause prejudice to children by reason of the fact that their mother and father were not in a legal marriage when they were born - a matter that the children themselves had no choice or chance to correct. Rather, it can be said that a notion that all children must be given respect as individuals and that their rights must be protected has been established.
Taken from Akiko, Ejima, "Emerging Transjudicial Dialogue on Human Rights in Japan- Does It Contribute to the Production of a Hybrid of National and International Human Rights?," Departmental Bulletin Paper, Meiji University