In a representative democracy, the value of one vote is supposed to be more or less equal. In the 2001 Upper House election, however, one vote in rural districts carried much greater weight than it did in urban districts; in an extreme case, one ballot in Tottori Prefecture was worth 5.06 ballots in Tokyo. Lawyers filed suits demanding the annulment of the voting, but the Supreme Court has rejected the request -- with serious reservations.

The ruling, delivered last week, said the seat distribution in the election does not violate the Constitution. But six of the 15 judges on the Grand Bench said that these wide vote-value disparities are unconstitutional because they contravene the principle of equality under the law. And four of those who supported the arrangement warned, in effect, that they might reverse their judgment if the inequalities are not corrected by the next Upper House election in July.

Wide imbalances in vote value existed in other Upper House elections as well, but the Supreme Court stopped short of declaring them unconstitutional, as it did in the latest case. This time around, however, its "patience" seems to have been stretched to the limit, with as many as 10 judges (including the six who disagreed outright) taking a critical stand. The Diet should reallocate seats before the July election.

The Supreme Court also approved Upper House seat arrangements twice in the past, in 1983 and 1996, citing some of the characteristics of the Upper House election system. The latest majority opinion takes a similar position, saying that the gap in one vote's worth is not so wide as to "exceed the limits of the Diet's legislative discretion."

The ruling gives two characteristics of an Upper House election. The first is the emphasis on regional representation. Voting in Upper House districts, it says, is meant to reflect collectively the views of residents in the prefectures -- traditional regions that represent the broadest geographical unit of administration - in national politics; rezoning some of these districts could compromise this aim.

The other characteristic is the fact that half of the Upper House is elected every three years. Because of this, the number of seats in each district must be even (according to this opinion, the number must be at least two). It is therefore not always possible, the ruling says, to allocate seats in proportion to populations.

It is doubtful, however, whether these features outweigh a glaring vote-value inequality that exceeds five times the weight in densely populated districts. The focus on regional representation is to be respected, but there seems to be no convincing reason why seats must be allocated at the prefectural level. Other methods of allocation can be devised to create a more equitable election system.

On the other hand, the ruling has unanimously supported the "open list" voting system for the proportional representation section of the Upper House election -- a new system that allows voters to cast ballots for either a party or a candidate. Seats are distributed to parties according to the total number of votes collected by each party and its candidates.

Many voters, however, are dissatisfied with this formula. They are unhappy, for example, that votes cast for a candidate are counted as votes for the party to which the candidate belongs. Many are also disappointed that some candidates elected from the proportional representation constituency switched their party affiliations after the voting.

Regarding the seat distribution issue, a statement made by one dissenting judge, a former secretary general of the Supreme Court, is especially notable. "Removing obstacles in the democratic system," he said, "is the role of the judiciary." Indeed, given that 10 of the 15 judges are critical of the existing vote-value imbalance, the court could have gone a step further and called it unconstitutional.

It is said that the Supreme Court, in deference to the legislative power of the Diet, rarely exercises its right of judicial review -- a tendency that scholars call "judicial passivism." Some legislators believe, as noted in a 2002 report from a Lower House panel on constitutional research, that this tendency could be detrimental to the smooth implementation of the Constitution.

There is also some truth to the view that such passivism has given the Diet an excuse for avoiding legislative action. The latest ruling is a case in point. There is, indeed, a need for the Supreme Court to assume a new attitude -- "judicial positivism." The Diet, for its part, needs to exercise its lawmaking power more positively. The first step to take is to undertake a thorough review of Upper House seat distribution.