Regarding the establishment, regent Yasutoki wrote two letters ('Yasutoki shosokubun') to his younger brother Shigetoki HOJO who was stationed at Rokuhara Tandai (an administrative and judicial agency in Rokuhara, Kyoto) in Kyoto, stating the spirit and purpose of shikimoku (law code).
制定に関して、執権泰時は六波羅探題として京都にいた弟の北条重時に宛てた2通の書状（「泰時消息文」）で、式目の精神・目的を述べている。