Thanks to the First Amendment, Americans enjoy a rare privilege: the constitutional right to lie. And although controversial, they should continue to enjoy this right. When commentators and politicians discuss misinformation, they often repeat five words: "fire in a crowded theater." Though governments can, if they choose, attempt to ban harmful lies, propaganda, misinformation, and disinformation, how effective will their efforts really be? Can they punish someone for yelling "fire" in a crowded theater—and would those lies then have any less impact? How do governments around the world respond to the spread of misinformation, and when should the US government protect the free speech of liars? In Liar in a Crowded Theater, law professor Jeff Kosseff addresses the pervasiveness of lies, the legal protections they enjoy, the harm they cause, and how to combat them. From the COVID-19 pandemic to the 2016 and 2020 presidential elections and the January 6, 2021, insurrection on the Capitol building, Kosseff argues that even though lies can inflict huge damage, US law should continue to protect them. Liar in a Crowded Theater explores both the history of protected falsehoods and where to go from here. Drawing on years of research and thousands of pages of court documents in dozens of cases—from Alexander Hamilton's enduring defense of free speech to Eminem's victory in a lawsuit claiming that he stretched the truth in a 1999 song—Kosseff illustrates not only why courts are reluctant to be the arbiters of truth but also why they're uniquely unsuited to that role. Rather than resorting to regulating speech and fining or jailing speakers, he proposes solutions that focus on minimizing the harms of misinformation. If we want to seriously address concerns about misinformation and other false speech, we must finally exit the crowded theater.