28 CFR §541.40

1. (a)In an effort to maintain a safe and orderly environment within its institutions, the Bureau of Prisons operates control unit programs intended to place into a separate unit those inmates who are unable to function in a less restrictive environment without being a threat to others or to the orderly operation of the institution. The Bureau of Prisons provides written criteria for the:
   1. (1)Referral of an inmate for possible placement within a control unit;
   2. (2)Selection of an inmate for placement within a control unit;
   3. (3)Regular review of an inmate while housed in a control unit; and
   4. (4)Release of an inmate from a control unit.
2. (b)The Bureau of Prisons provides an inmate confined within a control unit the opportunity to participate in programs and activities restricted as necessary to protect the security, good order, or discipline of the unit.