X v. Y

In 1947, Japan’s legislature revised inheritance laws to introduce a system of inheritance whereby the surviving spouse and all the children of a decedent would be heirs. When that revision was completed, however, an older provision was carried through as Civil Code 900(4) (Article 900(4)), according to which the inheritance share of a child who was born out of wedlock was one half of the share of a child born in wedlock. Japan’s legislature considered societal norms and cultural traditions from both inside and outside Japan when maintaining the diminished shares for children born out of wedlock. Since that time, societal opinions and the laws of other nations relaxed with regards to children born out of wedlock, and Japanese courts recognized those facts as early as 1995. In July 2001, P died with four surviving children: X1 and X2 (plaintiffs), who were born in wedlock, and Y1 and Y2 (defendants), who were born out of wedlock. X1 and X2 petitioned the courts for instructions on the correct division of shares. The Tokyo High Court held that P’s estate should be divided and distributed in accordance with the language of Article 900(4). Y1 and Y2 appealed to the Japan Supreme Court, arguing that Article 900(4) was unconstitutional under Article 14 of the Japanese constitution, which required equality under the law unless discriminatory treatment had reasonable grounds.