Japan's top court on Wednesday ruled a law requiring married couples to have the same family name is constitutional, rejecting plaintiffs who sought the right to keep separate surnames, local media said. 

The plaintiffs -- three couples -- submitted marriage registration documents with different surnames for wives and husbands in 2018. But municipal governments refused to accept the documents, the Mainichi Shimbun reported.

The plaintiffs argued requiring married couples to choose a single name "is against equality under the law and freedom of marriage, which are guaranteed by the constitution."

The ruling is in line with a 2015 Supreme Court decision that also found the law constitutional but urged MPs to discuss a bill addressing growing calls for flexibility on the issue.