Many academics, upon encountering a book on deference by a leading legal theorist, would assume that the book was still another contribution to a long and prominent debate about the existence (or not) of an obligation to obey the law. But that would be a mistake. In fact, this is a book not about obligation or obedience but about deference, and it is precisely in that difference that the significance of Philip Soper’s book lies. Especially in law, where the Supreme Court (sometimes) defers to the factual, legal, and even constitutional determinations of Congress and administrative agencies, where appellate courts (sometimes) defer to the findings of fact and law of trial courts, and where trial courts (sometimes) defer to the judgments of juries, conflating deference with obedience is plainly an error. It is the signature contribution of this book that it analyzes in great depth and with impressive nuance a concept so central to law, yet so often ignored because of the arguably disproportionate attention that legal philosophy has paid to the question of obedience.