Under the Constitution of the Empire of Japan, among the emperor's action, it was established as 'In order to convey the emperor's important affairs and intentions regarding prerogative enforcement, the imperial rescript shall be used, excluding other forms.'
大日本帝国憲法のもとでは、天皇の行為のうち「皇室ノ大事ヲ宣誥（せんこう）シ及大権ノ施行ニ関スル勅旨ヲ宣誥スルハ別段ノ形式ニ依（よ）ルモノヲ除クノ外詔書ヲ以（もつ）テス」るものと定めていた。