The Supreme Court ruled on Wednesday that the current electoral system used by the House of Representatives is constitutional, rejecting claims it violates the basic law for failing to provide equality due in part to disparities in the value of citizens' votes.
The ruling is the first by the Supreme Court on the constitutionality of the electoral system, which combines single-seat constituencies with proportional representation. It upholds rulings handed down on suits by the Tokyo High Court.
Presiding over the top court's 15-justice Grand Bench, which voted 9-5 against the charges, Chief Justice Shigeru Yamaguchi rejected demands that the October 1996 general election be declared invalid.
One justice did not participate in the decision because he was involved in mapping out the electoral system.
About 60 plaintiffs from five prefectures in the Kanto region filed the suits claiming the electoral system violates the Constitution because of large disparities in the number of voters per constituency.
The plaintiffs -- representing voters in Tokyo, Kanagawa, Chiba, Saitama and Tochigi prefectures -- also said the electoral system fails to properly reflect voters' will.
The October 1996 general election was the first to take place under the new electoral system.
The ruling was based on the views of the nine justices. The justice who did not take part in the ruling was Takao Ode.
The other five justices judged the electoral system unconstitutional because "the population disparity (among constituencies) is too large."
Under the election system, candidates are allowed to run in both single-seat constituencies and for proportional representation. So even if candidates are defeated in the single-seat constituencies, they can still be elected to the Lower House through proportional representation.
The Supreme Court ruled that the arrangement giving candidates a second chance at being elected was a "natural result" of the electoral system.