Judicial review of statutes on constitutional grounds is affected by a cluster of doctrinal practices that are generally accepted, but not very well explained, by the courts and not entirely consistent with each other. Courts usually judge statutes “as applied” rather than as written;See generally Michael C. Dorf, Facial Challenges to State and Federal Statutes, 46 STAN. L. REV. 235 (1994); Marc E. Isserles, Overcoming Overbreadth: Facial Challenges and the Valid Rule Requirement, 48 AM. U. L. REV. 359 (1998). they favor “severance” of valid applications of statutes from invalid or possibly invalid applications when possible;See generally Mark Movsesian, Severability in Statutes and Contracts, 30 GA. L. REV. 41 (1995); John Copeland Nagle, Severability, 72 N.C. L. REV. 203 (1993); Robert Stern, Separability and Separability Clauses in the Supreme Court, 51 HARV. L. REV. 76, 82–106 (1937). and they interpret statutes in ways that avoid constitutional difficulty.See generally Frederick Schauer, Ashwander Revisited, 1995 SUP. CT. REV. 71; Adrian Vermeule, Saving Constructions, 85 GEO. L.J. 1945 (1997). These overlapping practices presumably are intended to preserve legislation, and hence are associated with a modest conception of the role of courts in government. Yet they are not always modest in operation. Several commentators have equated the practices mentioned in the text to judicial revision of statutes. See Dorf, supra note 1, at 292–93 (severance results in a “judicially rewritten law”); Nagle, supra note 2, at 220 (the product of severance is “akin to a new statute”); Schauer, supra note 3, at 80–81 (narrowing construction is a form of “redrafting”).