Page:Arizona State Legislature v. Arizona Independent Redistricting Comm’n.pdf/26

22 State, “after any apportionment,” had not redistricted “in the manner provided by the law thereof.” The 1941 provi­sion, like the 1911 Act, thus accorded full respect to the redistricting procedures adopted by the States. So long as a State has “redistricted in the manner provided by the law thereof ”—as Arizona did by utilizing the independent commission procedure called for by its Constitution—the resulting redistricting plan becomes the presumptively governing map.

The Arizona Legislature characterizes §2a(c) as an “obscure provision, narrowed by subsequent developments to the brink of irrelevance.” Brief for Appellant 56. True, four of the five default redistricting procedures—operative only when a State is not “redistricted in the manner pro­vided by [state] law”—had “become (because of postenact­ment decisions of this Court) in virtually all situations plainly unconstitutional.” Branch v. Smith, 538 U. S. 254, 273–274 (2003) (plurality opinion). Concretely, the default procedures specified in §2a(c)(1)–(4) contemplate that a State would continue to use pre-existing districts following a new census. The one-person, one-vote principle an­nounced in Wesberry v. Sanders, 376 U. S. 1 (1964), how­ever, would bar those procedures, except in the “unlikely” event that “the decennial census makes no districting change constitutionally necessary,” Branch, 538 U. S., at 273 (plurality opinion).

Constitutional infirmity in §2a(c)(1)–(4)’s default proce­dures, however, does not bear on the question whether a State has been “redistricted in the manner provided by [state] law.” As just observed, Congress expressly