28 CFR 571.30: Purpose and scope.

The Bureau of Prisons may release an inmate whose release date falls on a Saturday, Sunday, or legal holiday, on the last preceding weekday unless it is necessary to detain the inmate for another jurisdiction seeking custody under a detainer, or for any other reason which might indicate that the inmate should not be released until the inmate's scheduled release date.

(a) The release authority for inmates convicted of offenses occurring prior to November 1, 1987 is pursuant to 18 U.S.C. 4163. The number of days used under 18 U.S.C. 4163 may not be added to the number of days remaining to be served to release an inmate “as if * * * on parole” (18 U.S.C. 4164) who would otherwise have been released by expiration of sentence.

(b) The release authority for inmates sentenced under the provisions of the Sentencing Reform Act of the Comprehensive Crime Control Act of 1984 for offenses committed on/or after November 1, 1987 is pursuant to 18 U.S.C. 3624(a).