令和7(行ケ)2 人口比例選挙請求事件

Following the October 26, 2025, general election for Japan's House of Representatives, the maximum disparity in vote value between the most and least populated single-seat districts reached 2.06 to 1. A group of voters and constitutional scholars, led by Hiroyuki Uewaki, filed a lawsuit with the Tokyo High Court seeking to invalidate the election results. They argued that such malapportionment violated the equality principle enshrined in Article 14 of the Constitution. The case was appealed to the Supreme Court (Reiwa 7 (Gyo-Ke) 2). In its ruling, the Grand Bench acknowledged that the disparity constituted a "state of unconstitutionality" but declined to nullify the election, emphasizing the need for the Diet to promptly address the unjustifiable population gap. The court stressed that continued legislative inaction could compel a different remedy in future cases.

The Supreme Court Grand Bench declared the election to be in a "state of unconstitutionality" but dismissed the claim to void the results. It directed the Diet to rectify the malapportionment without delay, while stopping short of invalidating the election.

Whether the substantial vote-value disparity among electoral districts infringed the constitutional guarantee of equality (Article 14) and whether the election must be declared void as a result.

The ruling intensified public and political pressure for fundamental electoral reform, including redrawing district boundaries and revisiting the mixed-member system. It underscored the judiciary's delicate balance between respecting legislative discretion and enforcing constitutional rights, fueling ongoing debates about the legitimacy of electoral outcomes in a rapidly shifting demographic landscape.