After the horrific end of World War II in the East, the Japanese decided to replace the draconian Meiji Constitution agreed to in 1889. But the new draft was itself not new; it was based on the draft imposed on the Japanese cabinet by the United States in 1946.
The document gave sovereignty to the people rather than the Emperor, who was now to be seen only as a symbol of state, similar therefore to the European monarchies, which are ‘constitutional’ rather than ‘absolute’. In January of 1946 the Emperor Hirohito had announced that he was no longer divine. Emperor’s divinity had not before been questioned by the Japanese people.
In contrast to the 1889 constitution, there would now be a bi-cameral Government or Diet, to which cabinets and committees would be directly responsible. It would immediately become the sole law-making body in the state. The Lower House or congress would have superiority over the Upper House or senate. It could suppress any veto by the Upper House simply by re-passing a disputed Bill with a two-thirds majority.
Both houses could however choose the Prime Minister, which meant in practice that the PM would come from the party in power. Governing elites in the pre-war period had always opposed this concept, whereas now most cabinet ministers had to be civilian and members of the Diet.
The Peace Constitution provided a strong guarantee of Civil Rights, including votes for women, and those rights could not be altered by law. But by far the most controversial section of the Constitution was the Peace Clause (No. 9) which renounced war as a sovereign right of the nation, and made provision for permanent disarmament.
Laws can be interpreted in different ways however, and No. 9 was subjected to various interpretations subsequently, leading to the creation of the self-defence forces, to be used only for the defence of the homeland.
Moreover, the Constitution could be amended by a two-thirds majority of both Houses, followed by approval from a majority of voters. It was formally adopted by Hirohito on 3 November, 1946 and became effective on 3 May, 1947. It has yet to be amended.