The Director of the Administrative Office of the United States Courts shall pay each justice or judge of the United States, and each retired justice or judge recalled or designated and assigned to active duty, while attending court or transacting official business at a place other than his official duty station for any continuous period of less than thirty calendar days (1) all necessary transportation expenses certified by the justice or judge; and (2) payments for subsistence expenses at rates or in amounts which the Director establishes, in accordance with regulations which the Director shall prescribe with the approval of the Judicial Conference of the United States and after considering the rates or amounts set by the Administrator of General Services and the President pursuant to
section 5702 of title 5. The Director of the Administrative Office of the United States Courts shall also pay each justice or judge of the United States, and each retired justice or judge recalled or designated and assigned to active duty, while attending court or transacting official business under an assignment authorized under chapter 13 of this title which exceeds in duration a continuous period of thirty calendar days, all necessary transportation expenses and actual and necessary expenses of subsistence actually incurred, notwithstanding the provisions of
section 5702 of title 5, in accordance with regulations which the Director shall prescribe with the approval of the Judicial Conference of the United States.