The Declaration of War and the Imperial Diet (December 1941)

In the autumn of 1941 the negotiations between Japan and the United States reached deadlock. After the Tojo Hideki cabinet was formed in October, the 77th (extraordinary) session of the Imperial Diet was convoked by an imperial rescript of 28 October for a term of five days; it was convened on 15 November and sat from 16 to 20 November, passing measures connected with preparations for war and laying the political groundwork for the decision to go to war. The earlier text stated that this session concluded on November 21, 1941; Japanese session lists give 20 November as the closing date. The Imperial Conference of 1 December formally decided on war against the United States, Britain and the Netherlands.

On December 8, 1941 (Japan time), Japanese forces invaded Malaya and attacked Pearl Harbor. Emperor Hirohito's Imperial Rescript declaring war on the United States and the British Empire was issued the same day, about seven and a half hours after the attack on Pearl Harbor began, and was printed on the front pages of that day's evening newspapers. It asserted that China had disturbed the peace of East Asia for more than four years and that American and British economic pressure had left the Empire no course but to fight for its existence and self-defence. Under the Meiji Constitution the declaration of war was an imperial prerogative and required no vote of the Diet, and the Diet was not in session on 8 December. The earlier account — that the Diet formally approved the rescript on 8 December and that Prime Minister Hideki Tojo read it before the Diet that day to thunderous ovations from assembled members — is therefore not consistent with the record of sessions.

The Diet's formal response to the outbreak of war came at the 78th (extraordinary) session, which sat for only two days, 16 and 17 December 1941. Prime Minister Tojo and other ministers addressed the Diet on 16 December, and the houses quickly passed the government's wartime legislation, including the Temporary Law for the Control of Speech, Publication, Assembly and Association, which sharply restricted those freedoms; it was promulgated on 19 December, came into force on 21 December and was not repealed until October 1945. The 79th ordinary session was convened on 26 December. From this point the Diet's check on the government and the military became increasingly nominal, and Japan's formal entry into the Pacific War was complete.

After its issue, the rescript was reprinted in the press on the eighth day of every month throughout the war, to reaffirm resolve, until the surrender in 1945. The National Diet Building in which the Imperial Diet met, completed in 1936, remains the seat of Japan's parliament today.