The Tokyo District Court upheld Japan’s ban on dual citizenship on Thursday. The court rejected the case of Japanese expatriates living in Europe who had challenged the constitutionality of the ban in the first judicial decision concerning the issue.

The court sided with the Japanese government’s concern for national interests. Judge Hideaki Mori said that allowing dual citizenship for Japanese nationals “could cause conflict in the rights and obligations between countries, as well as between the individual and the state.” The decision will keep Japan in the group of about 50 other countries that do not allow their citizens to hold multiple citizenships.

The plaintiffs in the case were eight Japanese-born residents of Europe. They live in countries including Switzerland and France and had to obtain citizenship to continue working in their respective European countries. Their complaint, filed in March 2018, challenged the constitutionality of Japan’s Nationality Law. Article 11 of the law states that “[a] Japanese national shall lose Japanese nationality when he or she acquires a foreign nationality by his or her own choice.” The plaintiffs claimed that this provision violates several articles of the Japanese Constitution. The allegedly violated articles include Article 13, which guarantees the individual “right to life, liberty, and the pursuit of happiness,” and Article 22, which states that the “[f]reedom of all persons to move to a foreign country and to divest themselves of their nationality shall be inviolate.”

Article 13 of the Nationality Law requires Japanese citizens to “renounce [their] Japanese nationality by making notification” to the country’s Minister of Justice. However, the law has no penalties, and the level of enforcement has been uncertain. According to Japan Times, an estimated half a million Japanese citizens have permanent residency status in other countries despite the Nationality Law.

The plaintiff’s counsel plans to appeal the decision.