The Supreme Court ruling last week that the October 2017 Lower House election — in which the maximum disparity in the value of votes between electoral districts was 1.98 to 1 — was constitutional does not put an end to the problem in which a ballot in a less populous constituency carries as much as around twice the weight as one in a more populous district. Officials and lawmakers need to be reminded of the gravity of the problem — which distorts the representation of popular will in the Diet — and maintain constant efforts toward eliminating the disparity, which runs counter to the equality principle under the Constitution.

The decision by the top court — which had earlier ruled that the previous three Lower House elections in 2009, 2012 and 2014 were all in a “state of unconstitutionality,” while falling short of invalidating the vote results as unconstitutional — apparently reflects the improvements made to the disparity in the election last year. A 2016 amendment to the Public Offices Election Law, made in response to the repudiation of the vote value gap in the earlier elections, cut six seats from the Lower House and redrew the borders of 97 electoral districts to keep the maximum disparity within 2 to 1 for the first time since the current electoral system combining single-seat constituencies and proportional representation blocs was introduced in 1996. The maximum gap in the value of votes reached 2.3 to 1 in the 2009 election, 2.43 to 1 in 2012 and 2.13 to 1 in 2014.

The 2016 revision also calls for the introduction of a new system of distributing Lower House seats across constituencies that better represents the population dispersal among the nation’s 47 prefectures — although implementation of that system was delayed until it reflects the outcome of the 2020 national census. The new system is expected to keep the maximum disparity in vote value within 2 to 1, and the Supreme Court ruling, which dismissed the lawsuit filed by a group of lawyers demanding that the 2016 Lower House election be invalidated, noted that legislative steps have been taken to significantly narrow and stabilize the disparity.

But is a vote value disparity barely within the 2-to-1 threshold — which means voters in some constituencies have nearly double the power of those in others in sending their representatives to the Diet — really acceptable? The Supreme Court ruling was a divided decision, with four of the 15 justices giving dissenting views. Two of them noted that the 2017 election was in a “state of unconstitutionality” and two others deemed the election to be unconstitutional. One of them, Justice Tsuneyuki Yamamoto — a former director of the Cabinet Legislation Bureau — said the result of the election should be invalidated.

Yamamoto said the value of votes should in principle be equal between electoral districts, and that the maximum allowable gap due to such factors as rapid changes in population dispersal should be “around 20 percent.” An opinion by another dissenting justice, Keiichi Hayashi — to say a nearly double disparity in the value is votes is not unequal runs counter to common sense — sounds quite reasonable. Giving voters unequal power to elect lawmakers to the Diet is a serious problem that could cast doubts over the legitimacy of Diet decisions — particularly in dealing with issues that sharply divide public opinion.

As the population exodus from rural to urban areas continues unabated, attempts to correct the disparity in the value of votes between populous and less populous constituencies are greeted with opposition — often heard from among ruling Liberal Democratic Party lawmakers — that distributing Diet seats in proportion to the population dispersal will deprive voters in rural depopulated regions of representation in national politics. The LDP, which relies on organized votes in rural areas, has even come up with a draft amendment to the Constitution to say that at least one Upper House member must be chosen from each of the 47 prefectures in each election — after some pairs of less-populated prefectures were combined into united constituencies in the effort to trim the gap in the value of votes in the chamber.

That is indeed a legitimate concern, but that should not be turned into an excuse for leaving the problem of vote value disparity unaddressed. In his dissenting opinion, Justice Yamamoto noted that it would be “difficult or effectively impossible” to realize equality in the value of votes as long as the demarcation of electoral districts is based on existing prefectural or municipal borders, and called for the introduction of an electoral system that either has one nationwide electoral district or divides the nation into regional blocs. Equalizing the value of people’s votes will need to involve broad discussions on an overhaul of the Diet electoral system.