Japan's top court rules that couples must share a last name, marking a huge setback for gender equality in the country

• Japan's top court has ruled that it is constitutional to force married couples to share a last name.
• The law is an archaic 19th-century mandate that has resulted in 96% of married women taking their husband's name.
• A previous attempt by five women to challenge the law also failed in 2015.

Japan's highest court has upheld a 19th-century law that forces couples to share the same last name.

A bench of 15 justices at the Japanese supreme court rejected a petition from three Tokyo couples, who requested that they be allowed to keep their own surnames even after they get married.

Japan is the only country in the world to have such a ruling in its civil code, which stipulates that couples must choose at the time of marriage to adopt one surname, according to Japan's Ministry of Justice. The Meiji-era civil code was written in 1898, based on the Japanese tradition of a woman leaving her own family to marry into her husband's.

This mandate has resulted in an overwhelming 96% of Japanese women adopting their husband's surname after marriage, per a study conducted by the Japanese Ministry of Health, Labour, and Welfare in 2016. In principle, a husband can take his wife's name, but only 4% of married men chose to do so in 2019, according to numbers from Japan's Gender Equality Bureau.

Per Bloomberg, some women do continue to use their birth names in the workplace, but the conflict between their legal names and professional identities can cause administrative confusion.

The three couples claimed in their 2018 filing that not being able to keep separate surnames was a violation of their constitutional rights after local government offices rejected their marriage registrations filed with distinct last names. However, the Japanese supreme court ruled against the couples after a three-year process - upholding the mandate enshrined in the country's family registration system, and noting that the matter should be debated in the Japanese parliament instead.

NHK Japan spoke to one of the plaintiffs, Aya Takahashi, who told the outlet she felt "broken."

Takahashi's husband, Hiroshi Mizusawa, said he hoped his children would grow up in a world where they have the agency to keep their last names.

"It's the role of our generation to make this happen," Mizusawa said.

Defense attorney Fujiko Sakakibara, one of the lawyers representing the couples, told NHK: "It's a shame. The gender ratio of judges is also a problem - this ruling would not have been the case if half of the 15 judges were women."

Sakakibara was referring to 13 of the 15 judges being men.

This unsuccessful legal challenge was the latest attempt by Japanese people to challenge the law. A 2015 lawsuit against the government filed by five women also failed. At the time, Kaori Oguni and four women sued the Japanese government, seeking some $50,000 in damages for the distress of having to take their husband's name.

A Kyodo poll this year suggests the times have changed, and the law is what is holding people back. Around 60% of the 3,000 people aged 18 and above that the news organization polled said couples should be able to have separate surnames.

Opposition figure Jun Azumi has vowed to take up the matter during the next election, calling the court's decision "outdated," per a report by the Japan Times.