18 U.S. Code § 4046 - Shock incarceration program

The Bureau of Prisons may place in a shock incarceration program any person who is sentenced to a term of imprisonment of more than 12, but not more than 30, months, if such person consents to that placement.
(b) For such initial portion of the term of imprisonment as the Bureau of Prisons may determine, not to exceed 6 months, an inmate in the shock incarceration program shall be required to—
adhere to a highly regimented schedule that provides the strict discipline, physical training, hard labor, drill, and ceremony characteristic of military basic training; and
participate in appropriate job training and educational programs (including literacy programs) and drug, alcohol, and other counseling programs.
An inmate who in the judgment of the Director of the Bureau of Prisons has successfully completed the required period of shock incarceration shall remain in the custody of the Bureau for such period (not to exceed the remainder of the prison term otherwise required by law to be served by that inmate), and under such conditions, as the Bureau deems appropriate.
Statutory Notes and Related Subsidiaries
Authorization of Appropriations

Pub. L. 101–647, title XXX, § 3002, Nov. 29, 1990, 104 Stat. 4915, provided that:

“There are authorized to be appropriated for fiscal year 1990 and each fiscal year thereafter such sums as may be necessary to carry out the shock incarceration program established under the amendments made by this Act [see Tables for classification]”.