In March, the Supreme Court ruled that the Lower House election of August 2009 was unconstitutional due to a great difference in the value of a vote between populated and depopulated constituencies. But it refrained from nullifying the election results. Political parties must urgently reach a consensus on how to reduce the disparity in the vote value. There is not much time left because the term for the current Lower House members end in the summer of 2013.

In the 2009 Lower House election, in which the Democratic Party of Japan trounced the Liberal Democratic Party and became a ruling party, the maximum difference in the vote value between populated and depopulated constituencies was 1 to 2.3. This inequality was caused by the current apportionment system, in which one seat each is given to each prefecture out of the 300 seats for single-seat constituencies and then the remaining seats are distributed in accordance with each prefecture's population size. The Supreme Court said that this system should be abolished. As a first step, the DPJ government plans to submit a bill to abolish it to a Diet session that started Oct. 20.

The DPJ and the LDP take the position that priority should be given to rectifying the disparity in the vote value while retaining the current election system rather than overhauling it. The current election system combines a single-seat constituency system and a proportional representation system — with 300 seats allocated to single-seat constituencies and 180 others to proportional representation. The two parties also propose decreasing the number of seats from proportional representation.