28 CFR §552.20

The Bureau of Prisons authorizes staff to use force only as a last alternative after all other reasonable efforts to resolve a situation have failed. When authorized, staff must use only that amount of force necessary to gain control of the inmate, to protect and ensure the safety of inmates, staff, and others, to prevent serious property damage and to ensure institution security and good order. Staff are authorized to apply physical restraints necessary to gain control of an inmate who appears to be dangerous because the inmate: