18 U.S.C. § 3565 — Revocation of probation

(a) Continuation or revocation. Before probation expires or ends, if the defendant violates a condition, the court may, after a Rule 32.1 hearing and considering applicable section 3553(a) factors, (1) continue probation, with or without extending it or changing its conditions, or (2) revoke probation and resentence under subchapter A. (b) Mandatory revocation. If the defendant (1) possesses a controlled substance in violation of section 3563(a)(3); (2) unlawfully possesses a firearm, as defined in section 921, or violates a probation condition barring firearm possession; (3) refuses required drug testing, violating section 3563(a)(4); or (4) tests positive for illegal controlled substances more than three times in one year as part of testing, the court must revoke probation and resentence under subchapter A to a sentence including imprisonment. (c) Delayed revocation. The court's power to revoke and impose another sentence continues after probation ends for the time reasonably needed to decide matters arising before expiration, if a warrant or summons based on the alleged violation was issued before expiration.