What title did Douglas MacArthur hold while leading the Allied occupation of Japan after its surrender?

Douglas MacArthur held the title Supreme Commander for the Allied Powers while leading the Allied occupation of Japan.

MacArthur was appointed SCAP after Japan's surrender and directed the occupation from Tokyo. The title referred to the authority overseeing Allied occupation policy, although the occupation was primarily carried out by United States forces. MacArthur worked through Japan's existing government while imposing major political, legal, economic, and social reforms.

Occupation policies included demilitarization, trials of suspected war criminals, land reform, labor changes, and a new constitution. The Constitution of Japan took effect in 1947 and included parliamentary government and an important renunciation of war in Article 9.

SCAP is often used both for MacArthur's office and for the organization under his command. The title should not be confused with MacArthur's wartime position as Supreme Allied Commander of the Southwest Pacific Area.