The Supreme Court has dismissed an appeal by a group of people living in Europe who have challenged Japan's ban on its citizens also holding foreign nationality.

The decision by the Supreme Court's First Petty Bench, dated Thursday, will let stand lower court rulings that acknowledged the constitutionality of a legal requirement that Japanese who gain foreign nationality must give up their original citizenship.

The eight plaintiffs, who live overseas in countries including Switzerland and France, had argued that foreign nationality was necessary to facilitate their work and lives abroad. But they also had hoped to maintain their Japanese citizenship.

They argued that with more countries allowing multiple citizenship, the clause in Japan's nationality law that strips people of Japanese nationality violates the Constitution, which guarantees the right to pursue happiness and equality under the law.

The article effectively banning dual citizenship says, "If a Japanese citizen acquires the nationality of a foreign country at their own choice, that Japanese citizen loses Japanese citizenship."

The Tokyo District Court rejected the lawsuit in 2021, saying that permitting multiple citizenship "could cause conflict in the rights and obligations between countries, as well as between the individual and the state."

The court cited tax payment and diplomatic protection in other countries to be affected under such a system.

The Tokyo High Court in February this year dismissed an appeal by the plaintiffs.