Resolving a legal battle stemming from the 2004 House of Councillors election, the Grand Bench of the Supreme Court (which includes all fifteen Justices) handed down a 10 - 5 decision in favor of the Diet by determining that the difference in de facto weight accorded to votes from densely and sparsely populated districts was not unconstitutional.

Lawyers from Tokyo, Kanagawa, and Chiba prefectures challenged the results of the 2004 Upper House election on the basis of a vote in largely rural Tottori prefecture being “worth” 5.13 Tokyo votes. In other words, a candidate would need just over five times as many votes to get elected from Tokyo as he would from Tottori.

The case echoed a January 2004 9 - 6 decision on virtually the same issue. Back then, the disparity was 5.06 and the Justices warned the Diet to take steps to correct it. Steps were not taken then, but have been since the 2004 election, putting the disparity at 4.8 currently. The disparity, though, like the disparity in population between Japan’s rural and urban areas, may well continue to grow. Can Diet rules be changed as quickly as small towns are dying or young people are moving to the cities?