31 U.S.C. § 326: Availability of appropriations for certain expenses

(a) Under regulations prescribed by the Secretary of the Treasury, an appropriation for the Department of the Treasury available to pay travel expenses also is available to pay expenses to attend meetings of organizations related to the function or activity for which the appropriation is made. (b) The Secretary may approve reimbursement to agents on protective missions for subsistence expenses authorized by law without regard to rates and amounts established under section 5702 of title 5.