28 C.F.R. § 550.41
A program of urine testing for drug use shall be established in contract CTCs.
(a) Urine surveillance shall be conducted on all inmates serving their sentence in a contract CTC:
(3) Who are suspected of using drugs.
Center staff shall collect a minimum of six samples per month from an inmate who meets one or more of the criteria listed in paragraphs (a) (1) through (3) of this section.