The Supreme Court’s 15-member Grand Bench ruled March 23 that the vote-value disparity in the August 2009 Lower House election, which reached a maximum 2.30-to-1, was “in a state of unconstitutionality.”
Although the Grand Bench did not explicitly say the disparity was “unconstitutional,” it is the first such ruling by the Grand Bench since a combination of the single-seat constituency and proportional representation systems was introduced for Lower House elections in 1994. The ruling means that the Diet must quickly rectify the situation.
The Supreme Court ruling dealt with nine lawsuits filed by two groups of lawyers, who claimed that the disparity violates the constitutionally guaranteed equality before the law. In the 2009 Lower House election, in which the Democratic Party of Japan trounced the Liberal Democratic Party to become a governing party, the maximum vote-value disparity reached 2.30-to-1 between the Kochi No. 3 constituency (with the least number of voters) and the Chiba No. 4 constituency (with the largest number of voters). This means that a voter in the Chiba constituency had only about 0.4 of the vote value enjoyed by a Kochi constituent.
What is conspicuous about the latest ruling is that the Supreme Court said the Diet should quickly abolish the current seat apportionment system under which, out of the 300 Lower House seats for single-seat constituencies, one seat each is first given to the 47 prefectures and the remaining 253 seats are distributed in proportion to the population distribution. The ruling will also affect the Upper House elections because the Upper House uses a similar system.
The current system is designed to prevent underrepresentation of smaller populations in rural areas. The ruling said that the system has already lost rationality and is the main factor responsible for inequality in vote value.
It has been said that as long as single-seat constituencies are based on the boundaries of municipalities, it will be difficult to attain perfect electoral equality. To avoid both underrepresentation and over-representation, the Diet must take a radically new approach.
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