Two high courts ruled Tuesday that a less than twofold vote disparity in last October's Lower House election was constitutional, dismissing plaintiffs' calls to invalidate the outcome.
Presiding Judge Takeshi Yamamoto at the Sendai High Court's Akita branch said the electoral districts adopted in the House of Representatives election "took into account equality of the vote weight and were reasonable."
The same day Tokyo High Court issued a similar ruling allowing voting disparity created by the country's rural-urban population imbalance.
Government data showed voting weight disparities just before the general election stood at 1.98 between Tokyo's No. 13 single-seat constituency and Tottori Prefecture's No. 1 district.
The rulings were the second and third among 14 lawsuits filed simultaneously by two groups of lawyers, challenging the results of the Lower House election at high courts nationwide.
They follow the Jan. 19 ruling by the Naha branch of the Fukuoka High Court that the election was constitutional and valid because a disparity in the value of votes between constituencies fell below two for the first time since the current election system was introduced.
The current election system was revised in 1994 and introduced single-seat electoral districts coupled with proportional representation blocs.
All of the high courts are expected to hand down rulings, possibly by the end of March, and the Supreme Court is expected to rule on the matter by the end of 2018.
For the general elections in 2009, 2012 and 2014, which had vote disparities ranging from 2.13 to 2.43, the top court ruled they were "in a state of unconstitutionality" but decided not to nullify the outcomes.
The central government has since redrawn electoral districts to slash one seat from each of six prefectures to reduce the disparity.
The overall number of seats in the lower house was reduced to a postwar low of 465.