The Osaka High Court ruled Wednesday that the disparity of up to 4.77-fold in the weight of votes in July's Upper House election was unconstitutional but dismissed plaintiffs' demand that the election results in six western districts be nullified.
Also on Wednesday, the Nagoya High Court determined the disparity is "in a state of unconstitutionality," while rejecting plaintiffs' claims that the election results in three districts in central Japan should be invalidated.
The Osaka ruling covered Osaka, Kyoto, Hyogo, Nara, Shiga and Wakayama, while the Nagoya ruling covered Gifu, Aichi and Mie.
The rulings are among 14 similar lawsuits filed with high courts by groups of lawyers, on which six rulings had already been delivered.
On Tuesday, the Naha branch of the Fukuoka High Court also ruled that the disparity of up to 4.77-fold left the election "in a state of unconstitutionality" but rejected the demand that the result in Okinawa be invalidated.
A Hiroshima High Court branch ruled last month that the results of the election in Okayama should be invalidated due to an unconstitutional gap in the weight of votes, while five other rulings said the election was held "in a state of unconstitutionality."
The disparity in the number of eligible voters per Upper House member stood at 4.77-fold between Hokkaido, the district with the most voters, and Tottori, which has the fewest.