A Tokyo court today (March 25) ruled that current law requiring Japanese married couples to use the same surname is constitutional, dismissing a challenge to the 19th-century law on the grounds that it is damaging and discriminatory.

Last year, a group of plaintiffs including Yoshihisa Aono, CEO of software firm Cybozu, and three other plaintiffs filed suit seeking ¥2.2 million ($20,000) damages for what they called “psychological damage” for being forced to use their spouse’s names, and the costs of the expensive bureaucratic process of changing one’s name on official documents. The plaintiffs also claimed that by excluding Japanese married to foreigners from that law, the law is discriminatory and therefore unconstitutional.

Aono, the most high-profile proponent of the right for Japanese couples to retain their own names after marriage, is unusual among Japanese in taking his wife’s family name, Nishihata, after marriage, though in business he continues to use his own name.

Tomoshi Sakka, the lawyer representing the plaintiffs, said at a press conference (link in Japanese) with Aono after the district court ruling that he plans to appeal the decision. In a tweet, Aono said that his “positive interpretation” of today’s ruling is that the matter could now be taken all the way to the Supreme Court, and that he plans to make public opinion on the issue heard during local elections and Upper House parliamentary elections this year.

Japanese couples can only revert to using their own names after they divorce—a law that prompted one Tokyo woman interviewed last year by Quartz to divorce her husband in order to use her own name, instead of her husband’s, even though the two remain a couple. Another woman, who only has sisters, told the Japan Times last year (paywall) that her parents only wanted her to marry a man who would be willing to take her family name in order to continue the family name.

The court’s ruling is the first on the matter since 2015, when five women challenged the law on the grounds of gender discrimination. Japan’s top court ruled then that the law in question, Article 750 of the civil code, would be upheld as it did not harm ”individual dignity and equality between men and women,” and because maiden names can still be used informally.

The matter of allowing couples to keep using their own names also gained fresh momentum in 2018 when a top female judge on the Supreme Court publicly said that she had continued to use her maiden name after marriage when handing down judgments, following a rule change that first allowed lawyers, and later judges, to use their pre-marriage names for legal complaints and other documents.

A study released in early 2018 by Japan’s cabinet office showed that 42.5% of respondents aged 18 and above supported a revision to the law to allow married couples to keep their own names, up 7 percentage points from 2012. Those who were against it declined by the same margin to 29.3%. But under the firm control of the conservative Liberal Democratic Party, the justice ministry has said that the levels of support for the change don’t warrant moving quickly to amend the law.