Cite as: 558 U. S. ____ (2010) 9 Opinion of STEVENS, J. be devised on an ad hoc basis, and then leaps from this unfounded prediction to the unfounded conclusion that such complexity counsels the abandonment of all normal restraint. Yet it is a pervasive feature of regulatory sys­ tems that unanticipated events, such as new technologies, may raise some unanticipated difficulties at the margins. The fluid nature of electioneering communications does not make this case special. The fact that a Court can hypothesize situations in which a statute might, at some point down the line, pose some unforeseen as-applied problems, does not come close to meeting the standard for a facial challenge.6 The majority proposes several other justifications for the sweep of its ruling. It suggests that a facial ruling is necessary because, if the Court were to continue on its normal course of resolving as-applied challenges as they present themselves, that process would itself run afoul of the First Amendment. See, e.g., ante, at 9 (as-applied review process “would raise questions as to the courts’ own lawful authority”); ibid. (“Courts, too, are bound by the First Amendment”). This suggestion is perplexing. Our colleagues elsewhere trumpet “our duty ‘to say what the law is,’ ” even when our predecessors on the bench and our counterparts in Congress have interpreted the law differ­ —————— 6 Our cases recognize a “type of facial challenge in the First Amend­ ment context under which a law may be overturned as impermissibly overbroad because a substantial number of its applications are uncon­ stitutional.” Washington State Grange v. Washington State Republican Party, 552 U. S. 442, 449, n. 6 (2008) (internal quotation marks omit­ ted). Citizens United has not made an overbreadth argument, and “[w]e generally do not apply the strong medicine of overbreadth analy­ sis where the parties fail to describe the instances of arguable over­ breadth of the contested law,” ibid. (internal quotation marks omitted). If our colleagues nonetheless concluded that §203’s fatal flaw is that it affects too much protected speech, they should have invalidated it for overbreadth and given guidance as to which applications are permissi­ ble, so that Congress could go about repairing the error.