A bill may be submitted to the Diet either by a Diet member or by the Cabinet. The Cabinet may submit a bill before either house. Submitted bills are referred to an appropriate committee for deliberation. In the case of major legislation, however, the purpose of the bill is explained and subjected to questioning by Diet members in a plenary session before the bill is referred to a committee.
Committees play a central role in deliberating over legislation. The purpose of the bill is explained in the committee, the committee members direct questions at government ministers and other officials involved in drawing up the legislation, experts are called to testify, amendments are proposed, issues are debated, and in the end a vote is taken. Bills that make it through committee are presented to the plenary session as proposed legislation.
In the plenary session, the committee chairman presenting the bill summarizes the discussions in committee and reports on the results. Following that, the bill is debated and voted on.
A bill passed by one house is sent to the other. The bill only becomes law if it wins approval in both houses. Since most bills are proposed initially in the House of Representatives, the House of Councillors is generally the final venue for deciding the fate of proposed legislation.