Typically, we conceive of preliminary relief as a shield from liability for sanctions triggered by noncompliance with the law during the period when the preliminary injunctive relief was in effect. But is that true? The answer is uncertain. In one case, Edgar v. MITE Corp., Justice Stevens and Justice Marshall debated the question but the Court did not reach it. Leading academics have raised the question and noted that the Court has yet to provide an answer. The question is difficult because it implicates the separation of powers, federalism, and due process of law. The answer is vitally important to private citizens who challenge governmental action because their liberty and property are at stake—and the stakes can be very high. I argue that a preliminary injunction must serve as a defense to liability, and I address concerns raised by that conclusion.