Section 549.40 - Purpose and scope(a) This subpart describes procedures for voluntary and involuntary psychiatric evaluation, hospitalization, care, and treatment, in a suitable facility, for persons in Bureau of Prisons (Bureau) custody. These procedures are authorized by 18 U.S.C. Chapter 313 and 18 U.S.C. 4042 .(b) This subpart applies to inmates in Bureau custody, as defined in 28 CFR part 500.