Japan's top court yesterday held unconstitutional some district polls in the 2012 election that brought Prime Minister Shinzo Abe to power because of wide gaps in the weight of rural and urban votes, but stopped short of invalidating the result.
Holding the elections invalid could have sparked political chaos since no precedent exists, but few had expected the Supreme Court to do so. Yesterday's court decision leaves the issue of reforms in lawmakers' hands.
Noting that changes made since last year's election had not addressed fundamental problems with distribution, the court urged parliament to tackle further reform.
"It is necessary to continue to steadily deal with the issue of fixing the electoral system," Kyodo news agency quoted the court as saying.
Critics say Japan's electoral system gives more influence to rural voters, many of them elderly, than to younger city dwellers, so driving politicians to push for policies favouring welfare and protectionism over economic growth.
The system has been credited with keeping Abe's Liberal Democratic Party in power for most of the past 60 years.
"Election reform is a bedrock issue for Abenomics," wrote Robert Feldman, chief economist at Morgan Stanley MUFG in Tokyo, ahead of the ruling.
"Without electoral reform that ends the major disparities of voter weights, the election incentives that have created and preserved vested interests would not change. Hence, both economic and fiscal reform would remain extremely difficult."