In 2018, the Liberal Democratic Party (LDP) narrowed the focus of its revised constitution to 4 items: explicitly mentioning the Self-Defense Forces, an emergency clause, the enhancement of education (which includes government aid to private schools), and the cancellation of “combined districts” in the House of Councillors elections. Combined districts in the House of Councillors elections were established in 2015 under the revised Public Offices Election Act. The revised law was implemented during the 2016 election. During this time, the population in rural areas was decreasing and this led to an imbalance in the value of the votes. The goal of the law was to correct the so-called “vote-value disparity.” Up until that point, the House of Councillors electoral districts were divided into units corresponding with Japan’s 47 prefectures (todōfuken). The revised law combined Tottori Prefecture, Shimane Prefecture, Tokushima Prefecture, and Kōchi Prefecture into a single electoral district. However, the LDP stressed that in order for the government to reflect the opinions of the residents from underpopulated areas, it was necessary to keep the prefectural electoral district units. The draft that the LDP published in 2012 stated that the establishment of electoral districts should take into account not only the population, but also “administrative districts and geography.” However, the criteria for “administrative districts and geography” was vague, and this aroused the suspicion that the LDP was creating electoral districts for their own advantage. As the unceasing migration from rural to urban areas continued, the LDP was criticized for trying to maintain the prefectural units to take advantage of its strong support base in rural areas, which would allow the party to have an advantage in the Diet. Another criticism is that the LDP is using its support for maintaining the 47 prefecture units as a trump card to gain cooperation from within the party for constitutional revision.
For a long time, the vote value disparity has been considered to go against the notion of equality prescribed in Article 14 of the Constitution. There have been frequent lawsuits because of this issue. In a 1976 lawsuit related to the House of Representatives election of 1972, the Supreme Court ruled for the first time that the House of Representatives elections were unconstitutional. After that, the vote disparity was still not eliminated, and lawsuits continued after the 2013 Upper House election. The disparity more than quadrupled. As mentioned previously, when the Public Offices Election Act was revised in 2016, the combining of districts resulted in fewer seats in the Diet for areas with smaller populations and more seats in the Diet for areas with large cities, such as Tokyo and Aichi Prefecture. The number of seats did not change. There was “an increase of 10, and a decrease of 10.” Later, in 2018, in an amendment led by the LDP, the number of seats in the House of Councillors was increased by 6, 4 of which were proportional representative seats. Because half the seats in the House of Councillors come up for election every three years, the “special frames” (tokubetsu waku) listing the voting preferences of each political party increased by 2. Two criticisms that arose from this were that this was a way to make up for the 2 seats lost in the Diet caused by combining districts and that LDP was using this change to help incumbents for their party’s interests. While the Supreme Court has continuously ruled that the vote value disparity is unconstitutional, it has been difficult for the LDP to gain support for their plan to cancel combined districts—which would increase the disparity—from members of other political parties. The insistence that the value of each vote be equal remains strong among members of the opposition party. Furthermore, the Kōmeitō, a member of the coalition government, has proposed an 11-proportional representation block district system. Originally, the establishment of electoral districts stipulated in the amendments to the Public Offices Election Act were considered sufficient, and many therefore believed that it was not necessary to revise the Constitution. Still, others have argued that “combined districts” violate Article 95 of the Constitution, which stipulates that “A special law, applicable only to one local public entity, cannot be enacted by the Diet without the consent of the majority of the voters of the local public entity concerned, obtained in accordance with law.”