TOKYO — In a widely watched ruling, Japan’s Supreme Court on Wednesday called last year’s parliamentary elections out of compliance with the Constitution because of inequalities in the size of voting districts, but stopped short of declaring the results invalid.

The court, the nation’s highest, was ruling on 16 separate lawsuits that had been filed by lawyers in different courts around Japan seeking to nullify results in December’s lower house elections, which returned to power the Liberal Democratic Party of Prime Minister Shinzo Abe. Those lawsuits sought to invalidate the results on the grounds that the number of voters in some districts, mostly rural ones, was far fewer than in other mostly urban districts, giving rural voters greater power in Parliament.

Earlier this year, two of those lawsuits won unprecedented decisions by lower courts that declared invalid the results in two districts. While there had been growing expectations that the Supreme Court might take a similarly activist stance on an issue that has long bedeviled Japanese elections, the judges did not go that far.

Instead, the court declared the elections to be “in a state of unconstitutionality” while requiring no remedial action beyond vaguely urging lawmakers to fix the problem. That is the same ruling that the court has made in several similar cases going back more than two decades.