ABSTRACT: Catherine Fisk Loyola Law School, Los Angeles; Erwin Chemerinsky University of Southern California abstract source The filibuster in the United States Senate imposes an effective supermajority requirement for the enactment of most legislation because sixty votes are required to bring a measure to a vote over the objection of any senator. Filibusters are ubiquitous but virtually invisible, for the contemporary Senate practice does not require a senator to hold the floor to filibuster; senators filibuster simply by indicating to the Senate leadership that they intend to do so. The prevalence and invisibility of this "stealth filibuster" dramatically affects which legislation is passed and which nominees are confirmed. The stealth filibuster also raises serious constitutional questions. Summarizing the historical development of Senate filibusters, Professors Fisk and Chemerinsky show that the nature and effects of filibusters have changed significantly as the Senate has grown larger and busier. They argue that, although dilatory debate has a history, the modern stealth filibuster is in significant respects unprecedented. Professors Chemerinsky and Fisk also assess the effects of the filibuster on Senate practice in light of empirical and public choice theories of congressional behavior. Based on this, they conclude that the filibuster is not alone among congressional procedures in being antimajoritarian and that it may counteract the antimajoritarian aspects of other congressional procedures. Professors Fisk and Chemerinsky then discuss the constitutionality of the filibuster. They first conclude that a judicial challenge to the Senate rules that permit it would be justiciable if brought by proper plaintiffs. They then conclude that, although the filibuster itself is not unconstitutional, the Senate rule that prohibits a majority of a newly elected Senate from abolishing the filibuster is unconstitutional because it impermissibly entrenches the decisions of past Congresses.