The Supreme Court ruling that disparity in the value of votes cast in the 2013 Upper House election was "in a state of unconstitutionality" — though it once again fell short of invalidating the election result itself — should serve as a stern rebuke on Diet members and their parties that continue to drag their feet in overhauling the electoral system even as time runs short before their self-imposed deadline for fixing the problem.

In the July 2013 poll that gave control of the upper chamber to the ruling coalition led by Prime Minister Shinzo Abe, the maximum gap in the value of votes between electoral districts reached 4.77 to 1. It means that people in the constituency with the smallest number of eligible voters per Upper House seat allocated to the district had 4.77 times more power in electing lawmakers than those in the constituency with the largest number of voters per seat. Such a disparity runs counter to the principle of equality under the Constitution and distorts the representation of popular will in the Diet.

When the Upper House election system was introduced in 1947, the maximum disparity in the vote value was 2.62 to 1, but the gap has since widened with the postwar population shift from rural to urban areas. It had reached as wide as 6.59-to-1 in the 1992 election, which four years later the Supreme Court determined for the first time was in a state of unconstitutionality — an expression that fell short of judging the election as unconstitutional and thereby illegal.