The Hiroshima high court determined that past result of general election in Dec. 2012 was invalid due to significant disparities in the weight of votes.
The Mainichi: Hiroshima court rules Dec. election invalid over vote disparity
In Japan, there has been some arguments about disparities in the weight of votes since 1990s. There are chronic disparities in votes, double in the lower house and even 5 times in the upper house. Some activists filed suits against the government repeatedly. Recently, the Supreme Court judged current circumstance as a violation of the constitution. Courts, however, had not negated the result of the election. This is the first time of declaration about the invalidation of voting by a court.
All parties published some comments after this judge. Some parties claim that the court decision is welcomed. It is a little ridiculous. I think that every lawmaker is responsible for the situation unimproved for a long time.
However, it is not so easy to change the system of voting by lawmakers themselves. They are concerned with the next election. It is acceptable that they are not willing to make any change to reduce the probability of reelection.
On the other hand, we citizen is also responsible. As I wrote before, voting rate is quite low in Japan. To claim about the disparity of the weight of votes without voting by ourselves is also ridiculous.
Now I am interested what the Supreme Court will judge about this. Generally Supreme Court in Japan is conservative I think. If the Supreme Court admits the decision of the High Court, Diet must be serious about this matter.