18 U.S.C. § 4047

(a) Any submission of legislation by the Judicial or Executive branch which could increase or decrease the number of persons incarcerated in Federal penal institutions shall be accompanied by a prison impact statement (as defined in subsection (b)). (b) The Attorney General shall, in consultation with the Sentencing Commission and the Administrative Office of the United States Courts, prepare and furnish prison impact assessments under subsection (c) of this section, and in response to requests from Congress for information relating to a pending measure or matter that might affect the number of defendants processed through the Federal criminal justice system. A prison impact assessment on pending legislation must be supplied within 21 days of any request. A prison impact assessment shall include— (1) projections of the impact on prison, probation, and post prison supervision populations; (2) an estimate of the fiscal impact of such population changes on Federal expenditures, including those for construction and operation of correctional facilities for the current fiscal year and 5 succeeding fiscal years; (3) an analysis of any other significant factor affecting the cost of the measure and its impact on the operations of components of the criminal justice system; and (4) a statement of the methodologies and assumptions utilized in preparing the assessment. (c) The Attorney General shall prepare and transmit to the Congress, by March 1 of each year, a prison impact assessment reflecting the cumulative effect of all relevant changes in the law taking effect during the preceding calendar year.