The Tokyo High Court on March 6 ruled that the apportionment for the Dec. 16 Lower House election was unconstitutional because of the extent of the disparity in single-seat constituency vote values between depopulated rural areas and populated urban ones.

Although the lawsuit was filed by a group of lawyers concerning the election in the Tokyo No. 1 constituency — and the court did not nullify the election results — the ruling’s implication is still significant as it casts strong doubt over the constitutional legitimacy of the election victories of many Lower House members. The Diet should reduce the vote-value disparity by immediately carrying out reapportionment.

On March 7, the Sapporo High Court ruled in a similar fashion. A series of other similar rulings with regard the constitutionality of the Lower House election results are likely to come by the end of this month. When that happens, the legitimacy of those Lower House members will be further weakened.

The Diet must prepare for the possibility that a court will declare the December election results null and void, thus necessitating a new round of elections after reapportionment. This would cause great confusion in Japanese politics.

In March 2011, the Supreme Court ruled that the August 2009 Lower House election, which brought the Democratic Party of Japan to power, was held “in an unconstitutional state” because of the great disparity in vote values, although it did not nullify the election results. The Tokyo High Court on March 6 said that the election in the Tokyo No. 1 electoral district was “illegal,” saying that the disparity in the weight of votes between depopulated rural areas and populated urban areas expanded from 2.304 times in the August 2009 Lower House election to 2.425 times in the December 2012 Lower House election.

It also pointed out that the number of constituencies where the disparity is 2.0 times or more increased from 45 to 72. Since the disparity of up to 2.0 times is regarded as acceptable, this means that the legitimacy of a quarter of the 300 Lower House members’ election wins in single-seat constituencies is in doubt.

In an effort to reapportion Lower House seats, the Diet enacted a bill to reduce one seat each in five prefectures on Nov. 16. But Prime Minister Yoshihiko Noda of the DPJ dissolved the Lower House the same day without waiting for reapportionment to be implemented. As the Liberal Democratic Party was calling for an early Lower House dissolution, both Mr. Noda and the LDP share responsibility for holding an election without reapportionment.

Fourteen high courts or high court branches are expected to make rulings by March 27 on lawsuits filed by lawyers’ groups on the legality of the December Lower House election.

If the legislature does not act quickly enough to reapportion Lower House seats, there will no other choice than for these courts to issue rulings either nullifying the election results or setting a specific deadline for reapportionment.