The Naha branch of the Fukuoka High Court ruled Tuesday that the disparity of up to 4.77-fold in the weight of votes in July's Upper House election was "in a state of unconstitutionality" but rejected the plaintiff's demand that the result in Okinawa be invalidated.

The decision followed similar rulings by the Takamatsu High Court and the Kanazawa branch of the Nagoya High Court on Monday. The court in Okinawa handed down the sixth such ruling among 14 similar lawsuits filed with high courts across Japan by groups of lawyers.

Presiding Judge Hidekazu Imaizumi said "excessive inequality" in the weight of votes existed at the time of the July election, which posed a question of unconstitutionality.

"But it cannot be said that (the Diet) did not correct the gap within a reasonable amount of time," he said.

A lawyer in Okinawa Prefecture argued that the vote-value gap that reached 2.30-fold in Okinawa compared with Tottori, which has the fewest voters, infringes on the equal-protection clause under the Constitution and thus the election outcome should be nullified.

The disparity in the number of eligible voters per Upper House member stood at 4.77-fold between Hokkaido, which has the most voters of any single district, and Tottori in the July election.

In late November, the Hiroshima High Court's Okayama branch ruled that the results of the Upper House election in Okayama Prefecture should be invalidated due to an unconstitutional gap in the weight of votes.

Earlier this month, the high courts in Hiroshima and Sapporo ruled the disparity was "in a state of unconstitutionality" but stopped short of declaring the election outcome should be invalidated.

Rulings on the eight remaining lawsuits are scheduled to be handed down before the end of the month.