After years of stalling, the Diet enacted a law Friday to revise Lower House electoral districts to reduce voting weight disparities between densely and sparsely populated precincts that had marred the credibility of national elections.
Based on population projections for 2020, the law will bring the maximum vote weight disparity between districts down to 1.999 to 1 — just under the 2-to-1 threshold that the Supreme Court has said would undermine the Constitution’s guarantee of equality for all under the law.
It will do this by cutting 10 seats from the House of Representatives and redrawing district boundaries. The changes will take effect on July 16 after a monthlong period to notify the public about the changes.
The amendment to the public offices election law will shrink the Lower House to a postwar low of 465 seats.
The 295 lawmakers currently elected from single-member districts will be reduced to 289, with Aomori, Iwate, Kagoshima, Kumamoto, Mie and Nara prefectures each losing a seat.
Another four seats will be cut from the proportional representation blocks, which will then account for 176 of the seats in the Lower House.
The move is expected to put off the next Lower House election by at least a few months. Prime Minister Shinzo Abe is considered highly unlikely to exercise his exclusive right to dissolve the chamber before the changes take effect, and his Liberal Democratic Party may need further time to sort out its candidates.
A Lower House election was last held in December 2014. House of Representatives members have a four-year term but a snap election can be called before their term expires.
In line with a Lower House election reform law enacted last year, the districts are expected to be revised again after the results of the 2020 census are released. This will result in the adoption of a different seat apportionment technique called the Adams Method to more accurately reflect population differences between prefectures.
The method is named after John Quincy Adams, the sixth president of the United States of America, who is thought to have suggested it.