When the committee finishes its examination, deliberation continues at a plenary session of the House concerned. The same procedure involving deliberation and decisions both by a committee and a plenary is then followed by the second House. Except otherwise provided by the Constitution, a legislative bill becomes a law when it passes both the House of Representatives and the House of Councilors. The newly enacted law must be promulgated within 30 days from the date on which the leader of the House that examined the bill second submits it to the Emperor via the Cabinet. As to the promulgation, it is done after a Cabinet decision to do so, and by publication in an official gazette .
Promulgation is to ensure that a newly enacted law becomes widely known by the public.
In other words, it is an act whereby the people is enabled to know the law. A law must be promulgated before it actually takes effect. Laws usually stipulate in their attached clauses when they come into effect. When a law is promulgated, it is given a serial number and signed by both the state minister responsible for the law and the Prime Minister.