28 U.S.C. § 42
The Chief Justice of the United States and the associate justices of the Supreme Court shall from time to time be allotted as circuit justices among the circuits by order of the Supreme Court. The Chief Justice may make such allotments in vacation.
A justice may be assigned to more than one circuit, and two or more justices may be assigned to the same circuit.
28 U.S.C. § 42
HISTORICAL AND REVISION NOTES Based on title 28, U.S.C., 1940 ed., §215 (Mar. 3, 1911, ch. 231, §119, 36 Stat. 1131; Dec. 23, 1944, ch. 724, 58 Stat. 925). The authority of the Chief Justice in vacation to assign a circuit justice to more than one circuit was extended by omitting the phrase "whenever by reason of death or resignation, no Justice is allotted to a circuit." The provision in section 215 of Title 28, U.S.C., 1940 ed., that, for the purposes of said section, the "District of Columbia shall be deemed to be a judicial circuit," was omitted, since the District of Columbia is made a judicial circuit by section 41 of this title. The last paragraph was added to make clear the intent of Congress that the powers of the Court to assign the justices among the several circuits should be completely flexible.Changes were made in phraseology.