The power of the shugo during the Kamakura period was prescribed by the legal code for the warrior class: their power was limited to the military and law enforcement, such as the 'Taibon-sankajo no kendan-sata' (three official authorities given to the shugo over criminal cases: the prodding of lower-ranking vassals to fulfill their duties as obanyaku, i.e., security guards, in Kyoto and Kamakura, the search and arrest of rebels and murderers) and the direction and supervision of obanyaku; the shugo was prohibited from participating in the administration of the kokuga and the kokuga's province, which the kokushi was authorized to perform.
鎌倉時代における守護の権能は御成敗式目に規定があり、大犯三ヶ条の検断沙汰（御家人の義務である鎌倉・京都での大番役の催促、謀反人の捜索逮捕、殺害人の捜索逮捕）および大番役の指揮監督という軍事・警察面に限定され、国司の権限である国衙行政・国衙領支配に関与することは禁じられていた。