Abstract: Formally, the law purports to be based solely in reasoned analysis, devoid of ideological bias or unconscious influences. Judges claim to act as umpires applying the rules, not making them. They frame their decisions as straightforward applications of an established set of legal doctrines, principles, and mandates to a given set of facts. As scholars who carefully study the law understand, that frame is a façade, and the impression that the legal system projects is an illusion. Oliver Wendell Holmes, Jr. made a similar claim more than a century ago when he wrote that “the felt necessities of the time, the prevalent moral and political theories, intuitions of public policy, avowed or unconscious, even the prejudices which judges share with their fellow-men, have a good deal more to do than the syllogism in determining the rules by which men should be governed.” A century later, though, we are much closer to understanding the mechanisms responsible for the gap between the formal face of the law and the actual forces shaping it. Over the last decade or so, political scientists and legal academics have begun studying the linkages between ideologies, on one hand, and legal principles and policy outcomes on the other. During that same period, mind scientists have turned to understanding the psychological sources of ideology. This book is the first to bring many of the world’s experts on those topics together to examine the sometimes unsettling interactions between psychology, ideology and law.