Legal scholar Jeff Kosseff examines lies and the First Amendment, asking when false statements deserve constitutional protection and when they can be punished. Drawing on cases from election disinformation to pandemic falsehoods to January 6th mythology, he traces how American law has struggled to balance free speech with the harms lies cause. Kosseff examines the 2012 Supreme Court decision in United States v. Alvarez, which struck down a law criminalizing lies about military honors, as a turning point in how courts approach false speech. His title refers to the famous dictum that the First Amendment does not protect falsely shouting fire in a crowded theater - except that, as Kosseff shows, the legal situation is far more complicated than that metaphor suggests. The book examines various categories of lies - defamation, fraud, perjury, deceptive advertising - showing how each has developed its own legal framework. Kosseff, who has written extensively on internet law, brings particular attention to how digital platforms have changed the scale and speed of lie propagation. For anyone concerned about misinformation and seeking to understand what legal tools exist (or don't) to address it, this work provides rigorous analysis grounded in constitutional doctrine and practical consequences.