44 U.S.C. § 1102: Printing to be authorized by law and necessary to the public business, not in excess of appropriation, and on special requisition filed with the Director of the Government Publishing Office

(a) A head of an executive department, or of an independent agency or establishment of the Government may not cause to be printed, and the Director of the Government Publishing Office may not print, a document or matter unless it is authorized by law and necessary to the public business. (b) Printing may not be done for an executive department, independent agency or establishment in a fiscal year in excess of the amount of the appropriation. (c) Printing may not be done without a special requisition signed by the chief of the department, independent agency or establishment and filed with the Director of the Government Publishing Office.