Vote-value disparity wider in 80% of Japan local assemblies than in 2019 elections

FUKUOKA -- The value of a vote between the most and least populous constituencies per lawmaker in Japan has widened further in some 80% of prefectures and cities set to have elections in April since the last unified local races in 2019, a Mainichi Shimbun study has shown.

Prefectures and government-designated major cities are divided into several constituencies for assembly elections, and the population per lawmaker varies from constituency to constituency. Each local assembly calculates the vote disparity based on the national census conducted once every five years, and examines whether corrective measures are necessary. Japan's latest census was in 2020.

The Mainichi Shimbun surveyed assembly secretariats of 47 prefectures and 20 government-designated cities in February and March 2023, and received responses from 67.

Looking at the 41 prefectures and 17 cities holding assembly elections in April, at the time the 2020 census results were released, 39 prefectures and 14 cities had a wider vote disparity compared to the last unified local elections. This is likely because underpopulated areas were losing more people, while urban areas saw population growth. Of these, 13 prefecture and nine cities subsequently took corrective measures, including revising assembly seat numbers and electoral district rezoning.

Meanwhile, 26 prefectures and five cities didn't take any corrective measures. Ten prefectures and five cities saw a wider vote-value gap than the 2019 elections despite taking such measures. In all, 36 prefectures and 10 cities will head into the April assembly elections, whose campaigns open on March 31, with wider vote disparities than in 2019.

Twenty-eight prefectures and one city will have a more than double vote-weight disparity. Of the 41 prefectures, Tokushima has the largest gap at 3.45 times, while the smallest seen in Saga at 1.46 times. While the vote-value disparity is over three times between the most and least populous constituencies in Tokushima, Hokkaido, Hyogo and Kanagawa prefectures, they all have special electoral districts based on the Public Offices Election Act where assembly seats can be allocated to underpopulated areas.

Asked why actions to correct vote-value gaps weren't taken, the Okayama Prefecture assembly secretariat said, "The voices of residents in mountainous areas need to be considered," while Niigata Prefecture answered, "Voters are used to the current electoral zones." Tochigi Prefecture said, "Combining single-seat districts would have significant consequences."

The election law stipulates that while the number of seats in each local assembly constituency should be set "proportional to the population," it also says "under special circumstances, it may be determined while taking into consideration the balance among regions, while having it broadly based on the population."

In recent rulings, the Supreme Court ruled the 2015 Chiba Prefectural Assembly election "constitutional" with the largest vote disparity at 2.51 times. However, the top court deemed the 2014 House of Representatives election with the largest gap of 2.13 times "in a state of unconstitutionality," showing the court tends to grant local assemblies broader discretionary authority.

Kumamoto University Vice President Hironori Ito, a political science professor versed in election systems, told the Mainichi, "In principle, local assembly elections are based on population ratios, and they have responsibilities in correcting (vote-weight disparity). While I understand that lawmakers don't want to fix this issue since it's related to their seats in the assemblies, we see many single-seat districts with no contest as a result, and this is concerning as it can create divergence from the will of the people."

(Japanese original by Hayato Jojima, Kyushu News Department)