Last year's House of Councilors election was ``unconstitutional''; Supreme Court Grand Bench calls for rectification of vote disparity

The Grand Bench of the Supreme Court (presiding judge: Yukihiko Imazaki) ruled on the 11th in 16 lawsuits in which two groups of lawyers sought to invalidate the election, stating that the 3.13-to-1 vote disparity in the July 2025 House of Councilors election was unconstitutional. He rejected claims that the election should be invalidated.

A majority opinion of 10 of the 15 judges who heard the case. Five people gave the opinion that it is ``constitutional.'' This is the first time the Supreme Court has ruled that an Upper House election is unconstitutional since the 2013 Upper House election, when the disparity was up to 4.77 times. The 2016, 2019 and 2022 elections were deemed constitutional. The ruling will force the Diet to take measures to correct disparities.

The ``vote disparity'' refers to the inequality in the value of a vote because the number of voters per member of Congress differs from district to district.

In the 2025 House of Councilors election, Kanagawa, which had the most voters per member, had 3.13 times as many voters as Fukui, which had the least. Compared to Fukui, the value of a voter's vote in Kanagawa was less than one-third.

Although it was said to be an “urgent issue,” it was not corrected.

In its 2023 ruling regarding the 2022 House of Councilors election, the Supreme Court described rectifying disparities as an "urgent issue" and urged the Diet to consider this, including a fundamental review. However, the 2025 House of Councilors election was held without any progress in correction, and the largest disparity (3.13 times) was wider than the 2022 House of Councilors election (3.03 times).

The Grand Court's ruling on the 11th pointed out that although it has been about 10 years since the introduction of the system of ``combining constituencies,'' which combines two constituencies into one, in order to rectify disparities, there is no prospect of further legal reform aimed at correcting the disparities. Despite the need to respond to ``urgent issues'' amid widening disparities, he said, the Diet's efforts have been ``resulting in the same debates over and over again, and I cannot help but evaluate them as deadlocked.''

In addition, even taking into account the difficulty of deciding on specific corrective measures and the fact that debate takes a certain amount of time, it was determined that the disparity in the 2025 House of Councilors election had "reached a level that could no longer be overlooked." It concluded that the disparity was unconstitutional.

On the other hand, the five judges ruled that the bill was constitutional, stating that it would take a considerable amount of time for the Diet to correct it while gaining the understanding of the people.

Lawsuits over the disparity in votes primarily focus on (1) how serious the disparity in the value of votes is, and (2) whether the National Diet is trying to rectify the disparity. If the degree of inequality is severe and there is no prospect of correction by the Diet, the court will judge the situation to be ``unconstitutional.'' If it is determined that the situation has not reached that point, it will be judged as ``constitutional.''

If the Diet does not take action even though the situation is already unconstitutional, and the court determines that it is ``beyond the limits of the Diet's discretion,'' it will be considered ``unconstitutional.''

In this case, out of 16 high court rulings in various regions, 11 were deemed ``unconstitutional'' because the Diet's efforts were insufficient. On the other hand, only 5 cases were deemed ``constitutional.''

In the lawsuit, the plaintiff's lawyers argued that the current election system does not treat every citizen equally, and that the Supreme Court should order the Diet to allocate seats in proportion to the population. He complained that the 2025 House of Councilors election was unconstitutional and invalid, citing the fact that the disparity had widened even further compared to the 2022 House of Councilors election, rather than making progress in rectifying it.

According to the provisions of the Public Offices Election Law, the Election Commission, which was the defendant in the lawsuit, explained, ``The reason that the disparity has not been corrected is because there are issues and constraints that need to be carefully considered.'' He maintained that the bill was constitutional, noting that discussions aimed at rectifying disparities were continuing in the Diet.