Emperor Hirohito issued a rescript on August 14, 1945 stating Japan would accept the Potsdam Declaration. This decision set the stage for Allied occupation and created the opening for major political reforms, including rewriting Japan’s constitutional system.
On October 4, 1945, the Supreme Commander for the Allied Powers (SCAP) ordered the removal of restrictions on political, civil, and religious liberties. The directive pushed Japan to repeal repressive laws and release political prisoners, signaling that democratization would be a core goal of the occupation.
On October 25, 1945, Japan established the Constitution Investigation Committee chaired by Jōji Matsumoto. The committee’s work reflected early efforts to revise the Meiji Constitution from within the Japanese government, before stronger occupation pressure shifted the process.
On December 15, 1945, SCAP issued SCAPIN-448, directing the abolition of government sponsorship and control of “State Shinto.” This reform aimed to separate religion from the state and weaken ideological tools that had supported wartime nationalism, helping clear the path for constitutional change.
On February 1, 1946, newspapers revealed a more liberal draft associated with the Matsumoto committee, triggering public debate and criticism. The negative reaction, including from occupation authorities, helped convince SCAP that Japan’s official revision effort was too limited.
On February 8, 1946, the Japanese side submitted its “Outline of Constitution Revision” to General Headquarters (GHQ/SCAP). GHQ rejected it as insufficient, which accelerated the shift toward an occupation-driven draft.
On February 13, 1946, GHQ’s Government Section presented its draft constitution to the Japanese government. The draft reflected the “MacArthur Three Principles,” including keeping the emperor while redefining his role, renouncing war, and eliminating feudal-era structures.
On April 10, 1946, Japan held a general election for the House of Representatives in which women voted for the first time. The election widened democratic participation and helped create a legislature with greater legitimacy to debate a new constitutional order.
On April 17, 1946, the Japanese government publicly announced its draft for a revised constitution, based on the GHQ draft but translated and adapted into Japanese legal language. Publication made the proposed reforms visible to the public and prepared the way for formal Diet deliberations.
On June 25, 1946, the constitutional revision bill was proposed and debated in the Imperial Diet. The months-long debate mattered because it was a key moment when Japanese legislators negotiated the text, including adding or strengthening rights-related provisions.
On October 29, 1946, the Privy Council approved the constitution after Diet passage. This step was part of the legal process required under the Meiji Constitution’s amendment rules, moving the document toward imperial ratification and promulgation.
On November 3, 1946, the Constitution of Japan was promulgated (formally issued) in the Official Gazette. Promulgation finalized the text and set a timeline for implementation, including the planned effective date in 1947.
On December 1, 1946, the Kenpō Fukyū Kai (Constitution Popularization Society) was officially established to spread understanding of the new constitution. Its public education work mattered because the reforms were wide-ranging, and successful implementation depended on broad public and official awareness.
On January 16, 1947, the revised Imperial House Law was passed in the last session of the Imperial Diet. The law mattered because the new constitution made the emperor a constitutional “symbol,” and succession and imperial-family rules now had to be clearly grounded in ordinary law under the new system.
On April 17, 1947, Japan promulgated the Local Autonomy Law (Law No. 67 of 1947). It created a framework for modern local government and elections, supporting the constitution’s promise of local self-government by defining powers and structures below the national level.
On April 25, 1947, Japan held the first general election to form the House of Representatives under the new constitution. This election helped convert constitutional principles—like popular sovereignty and representative government—into a working political system.
On May 3, 1947, the Constitution of Japan entered into force. It replaced the Meiji Constitution and reorganized government around popular sovereignty, guarantees of rights, and a parliamentary cabinet system, while redefining the emperor as the “symbol of the State.”
On May 3, 1947, the Cabinet Law took effect alongside the constitution, helping define how executive power would operate in practice. It reinforced that the Cabinet is collectively responsible to the Diet, supporting a clearer parliamentary cabinet structure than under the prewar system.
On May 24, 1947, Tetsu Katayama formed a coalition cabinet, commonly described as the first cabinet under the postwar constitution. This marked an early test of the new political rules in real governing conditions and underscored the shift toward party-based parliamentary leadership.
Constitution of Japan and Political Reforms (1946–1947)