Japan’s National Diet has two chambers: the House of Representatives and the House of Councillors. Both are made up of elected members and both debate laws and other national issues. But they are not simply two copies of the same legislature. The biggest differences are how quickly their membership can change after elections and how much power each chamber has when they disagree.
Members of the House of Representatives serve four-year terms. However, the House can be dissolved, which means their terms can end before the four years are over and a general election is held. The House has 465 members, elected through single-seat constituencies and proportional representation.
The House of Councillors works differently. Its members serve six-year terms, and the chamber cannot be dissolved. Instead, half of its members face election every three years. It has 248 members, elected through electoral districts and proportional representation. This means the entire House of Councillors never changes at once because of a single election.
Even if an election for the House of Representatives causes a major shift in Japanese politics, all members of the House of Councillors do not suddenly change as well. Because the two chambers are elected on different schedules, one election cannot completely reshape the entire Diet at the same time.
The two chambers also do not have exactly the same power. If they disagree over the national budget, approval of treaties, or the choice of prime minister, the decision of the House of Representatives can become the decision of the Diet after the required procedures are followed. If the House of Councillors rejects a bill, the House of Representatives can still pass it by approving it again with a two-thirds majority of members present. Only the House of Representatives can pass a no-confidence resolution against the Cabinet.
On paper, then, the differences between the two chambers are quite clear. But voters do not necessarily think about those institutional differences in detail every time they vote.
They may be more focused on which party they support or what a particular candidate is promising than on the role of the chamber itself. A voter may not consciously change the way they choose a candidate simply because the election is for the House of Representatives rather than the House of Councillors. The institutional roles are clearly different, but that difference may not play a large part in how an individual voter actually decides whom to support.
So if the House of Representatives has stronger powers in some areas, does that mean the House of Councillors is unnecessary?
Not really. As a rule, legislation is considered by both chambers. The House of Representatives is designed to reflect changes in election results more quickly. The House of Councillors, with no dissolution and only half its members elected at a time, provides more continuity even when the political climate changes sharply.
The difference is not simply that one chamber is more important than the other. Their different terms and election schedules allow them to respond to political change at different speeds.
