28 CFR § 0.142 - Per diem and travel allowances.
The Director of the Federal Bureau of Investigation, Director of the Bureau of Prisons, Commissioner of Federal Prison Industries, Inc., Commissioner of Immigration and Naturalization Service, Administrator of the Drug Enforcement Administration, Director of the Bureau of Alcohol, Tobacco, Firearms, and Explosives, Director of the United States Marshals Service, and Assistant Attorney General, Office of Justice Programs, as to their respective jurisdictions, and the Assistant Attorney General for Administration as to all other organizational units of the Department (including U.S. Attorneys), except as provided in paragraphs (f) and (g) of this section, are authorized to exercise the authority of the Attorney General to take final action in the following matters:
(a) Authorizing travel, subsistence, and mileage allowances under sections 5702–5707 of title 5 of the U.S. Code in accordance with regulations prescribed by the Administrator of General Services and the Assistant Attorney General for Administration.
(b) Fixing rates in accordance with sections 5702–5704 and 5707 of title 5, U.S. Code, and regulations prescribed by the Administrator of General Services and the Assistant Attorney General for Administration.
(c) Authorizing travel advances pursuant to 5 U.S.C. 5705 in accordance with the regulations prescribed by the Administrator of General Services and the Assistant Attorney General for Administration.
(d) Authorizing travel and transportation expenses, and, when applicable, relocation expenses for transferred employees, new appointees and student trainees, in accordance with 5 U.S.C. 5721–5733 and regulations prescribed by the Administrator of General Services and the Assistant Attorney General for Administration.
(e) Authorizing or approving, for purposes of security, the use of compartments or other transportation accommodations superior to lowest first-class accommodations under applicable travel regulations subject to 5 U.S.C. 5731.
(f) The heads of Offices, Boards and Divisions, in addition to the Bureaus, have the authority to approve the use of cash in excess of $100 in lieu of Government Transportation Requests in emergency circumstances, in accordance with regulations prescribed by the Administrator of the General Services Administration.
(g) The Director of the Federal Bureau of Investigation, the Director of the Bureau of Alcohol, Tobacco, Firearms, and Explosives, and the Administrator of the Drug Enforcement Administration are authorized to approve travel expenses of newly appointed special agents and the transportation expenses of their families and household goods and personal effects from place of residence at time of selection to the first duty station, in accordance with 28 U.S.C. 530 and regulations prescribed by the Assistant Attorney General for Administration.