TOKYO (AP) - Japan's Supreme Court ruled Wednesday that requiring married couples to have the same surname is constitutional, dealing a blow to a longtime effort for gender equality in choosing names.

The law does not say which partner must give up his or her name in marriage. In practice it has almost always been the woman who took the husband's name. Some women say that is unfair and feel as though their identity is lost.

In traditional marriage, one person, usually the woman, enters the household of the partner and is registered as a member of that household. Men are seen as more powerful in Japanese traditional culture. But as women increasingly have careers, some argue that changing surnames is confusing.

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Some Japanese women continue to use their maiden name professionally, even after their surnames are legally changed following marriage. Some couples simply don't register their marriages.

Kaori Okuni, one of the plaintiffs, said she was deeply disappointed.

"This has consequences for the future, meaning suffering for those who plan to marry and those who are set to be born," she told a news conference.

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In a separate case, the Supreme Court ruled that prohibiting women from remarrying for six months is unconstitutional.

The thinking behind that requirement was to prevent a woman who was possibly pregnant by one man from marrying a different person.

The court said that was outdated because of advances in science, such as DNA testing, that provide proof of the biological parent, Tomoshi Sakka, a lawyer for that case, told reporters outside the courtroom.

"The policy degraded women, and this is a step toward gender equality," he said.

The court found that a ban on remarrying exceeding 100 days was excessive. Sakka said he was optimistic that the change would be extended to less than 100 days in parliamentary discussions.

That was little comfort for some.

Akemi Ujitani, among a group of people gathered outside the Supreme Court building, broke into tears when the ruling was announced.

"This is about women's human rights," she said. "This is not right."