The Supreme Court ruled Wednesday that the Upper House election in the summer of 2013 bordered on being unconstitutional due to an "outrageous" disparity in the weight of votes between districts, but it rejected the plaintiff's demand to invalidate the result.

The ruling indicates again the judiciary's growing impatience with lawmakers' continued reluctance to rectify the inequality in vote values in national elections between heavily populated districts and their more sparsely populated counterparts.

The top court's decision is likely to provide reform-minded forces with further momentum to press for a full-fledged revamp of the electoral system, even as the nation prepares for the snap Lower House election slated for Dec. 14.