4 MOORE v. HARPER Syllabus for present purposes, the Court embraced the core principle espoused in Hildebrant and Smiley: Whatever authority was responsible for redistricting, that entity remained subject to constraints set forth in the State Constitution. The Court dismissed the argument that the Elections Clause divests state constitutions of the power to enforce checks against the exercise of legislative power. The basic principle of these cases—reflected in Smiley’s unanimous command that a state legislature may not “create congressional districts independently of” requirements imposed “by the state constitution with respect to the enactment of laws,” 285 U. S., at 373—commands continued respect. Pp. 15–18. (b) The precedents of this Court have long rejected the view that legislative action under the Elections Clause is purely federal in character, governed only by restraints found in the Federal Constitution. The argument to the contrary does not account for the Framers’ understanding that when legislatures make laws, they are bound by the provisions of the very documents that give them life. Thus, when a state legislature carries out its federal constitutional power to prescribe rules regulating federal elections, it acts both as a lawmaking body created and bound by its state constitution, and as the entity assigned particular authority by the Federal Constitution. Both constitutions restrain the state legislature’s exercise of power. This Court’s decision in McPherson v. Blacker, 146 U. S. 1, in which the Court analyzed the Constitution’s similarly worded Electors Clause, is inapposite. That decision did not address any conflict between state constitutional provisions and state legislatures. Nor does Leser v. Garnett, 258 U. S. 130, which involved a contested vote by a state legislature to ratify a federal constitutional amendment, help petitioners. That case concerned the power of state legislatures to ratify amendments to the Federal Constitution. But fashioning regulations governing federal elections “unquestionably calls for the exercise of lawmaking authority.” Arizona State Legislature, 576 U. S., at 808, n. 17. And the exercise of such authority in the context of the Elections Clause is subject to the ordinary constraints on lawmaking in the state constitution. Pp. 18–22. (c) Petitioners concede that at least some state constitutional provisions can restrain a state legislature’s exercise of authority under the Elections Clause, but they read Smiley and Hildebrant to differentiate between procedural and substantive constraints. But neither case drew such a distinction, and petitioners do not in any event offer a defensible line between procedure and substance in this context. Pp. 22–24. (d) Historical practice confirms that state legislatures remain