28 USC 296 – Powers upon designation and assignment
A justice or judge shall discharge, during the period of his designation and assignment, all judicial duties for which he is designated and assigned. He may be required to perform any duty which might be required of a judge of the court or district or circuit to which he is designated and assigned.
Such justice or judge shall have all the powers of a judge of the court, circuit or district to which he is designated and assigned, except the power to appoint any person to a statutory position or to designate permanently a depository of funds or a newspaper for publication of legal notices. However, a district judge who has retired from regular active service under section 371(b) of this title, when designated and assigned to the court to which such judge was appointed, having performed in the preceding calendar year an amount of work equal to or greater than the amount of work an average judge in active service on that court would perform in 6 months, and having elected to exercise such powers, shall have the powers of a judge of that court to participate in appointment of court officers and magistrate judges, rulemaking, governance, and administrative matters.
A justice or judge who has sat by designation and assignment in another district or circuit may, notwithstanding his absence from such district or circuit or the expiration of the period of his designation and assignment, decide or join in the decision and final disposition of all matters submitted to him during such period and in the consideration and disposition of applications for rehearing or further proceedings in such matters.