Watson v. Republican National Committee · ¶59

Two principles are important here. First, post-electionday receipt, considered on its own, does not conflict with the election-day statutes. See Part II, supra. Second, state law is preempted by the federal election-day statutes only “‘so far as the conflict extends.’” Foster, 522 U. S., at 69 (quoting Ex parte Siebold, 100 U. S. 371, 384 (1880), abrogated on other grounds by Glasgow v. Moyer, 225 U. S. 420 (1912)); see Siebold, 100 U. S., at 392 (Congress’s power to regulate elections “supersede[s]” state law “so far as it is exercised, and no farther”). So even if plaintiffs are right about Mississippi law, they would still lose the challenge they have pressed in this litigation: that post-election-day ballot receipt is itself unlawful.

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