Opinion of the Court
http://azredistricting.org/Maps/Final-Maps/default.asp (all Internet materials as visited June 25, 2015, and included in Clerk of Court’s case file). Less than four months later, on June 6, 2012, the Arizona Legislature filed suit in the United States District Court for the District of Arizona, naming as defendants the AIRC, its five members, and the Arizona Secretary of State. The Legislature sought both a declaration that Proposition 106 and congressional maps adopted by the AIRC are unconstitutional, and, as affirmative relief, an injunction against use of AIRC maps for any congressional election after the 2012 general election.
A three-judge District Court, convened pursuant to 28 U. S. C. §2284(a), unanimously denied a motion by the AIRC to dismiss the suit for lack of standing. The Arizona Legislature, the court determined, had “demonstrated that its loss of redistricting power constitute[d] a [sufficiently] concrete injury.” 997 F. Supp. 2d 1047, 1050 (2014). On the merits, dividing two to one, the District Court granted the AIRC’s motion to dismiss the complaint for failure to state a claim. Decisions of this Court, the majority concluded, “demonstrate that the word ‘Legislature’ in the Elections Clause refers to the legislative process used in [a] state, determined by that state’s own constitution and laws.” Id., at 1054. As the “lawmaking power” in Arizona “plainly includes the power to enact laws through initiative,” the District Court held, the “Elections Clause permits [Arizona’s] establishment and use” of the Commission. Id., at 1056. Judge Rosenblatt dissented in part. Proposition 106, in his view, unconstitutionally denied “the Legislature” of Arizona the “ability to have any outcome-defining effect on the congressional redistricting process.” Id., at 1058.
We postponed jurisdiction, and now affirm.
II
We turn first to the threshold question: Does the Ari-
