In this book, Adrian Vermeule shows that any approach to legal interpretation rests on institutional and empirical premises about the capacities of judges and the systemic effects of their rulings. He argues that legal interpretation is above all an exercise in decisionmaking under severe empirical uncertainty.

Thirty-five chapters describe various judgmental heuristics and the biases they produce, not only in laboratory experiments, but in important social, medical, and political situations as well. Most review multiple studies or entire subareas rather than describing single experimental studies.

Human reason is limited. Given the scarcity of reason, how should the power to make constitutional law be allocated among legislatures, courts and the executive, and how should legal institutions be designed? In Law and the Limits of Reason, Adrian Vermeule denies the widespread view, stemming from Burke and Hayek, that the limits of reason counsel in favor of judges making "living" constitutional law in the style of the common law. Instead, he proposes and defends a "codified constitution" - a regime in which legislatures have the primary authority to develop constitutional law over time, through statutes and constitutional amendments. Vermeule contends that precisely because of the limits of human reason, large modern legislatures, with their numerous and highly diverse memberships and their complex internal structures for processing information, are the most epistemically effective lawmaking institutions.

How do arbitrators decide in the face of the uncertainty of the law between alternatives which may be equally justified?

Ronald Dworkin once imagined law as an empire and judges as its princes. But over time, the arc of law has bent steadily toward deference to the administrative state. Adrian Vermeule argues that law has freely abandoned its imperial pretensions, and has done so for internal legal reasons. In area after area, judges and lawyers, working out the logical implications of legal principles, have come to believe that administrators should be granted broad leeway to set policy, determine facts, interpret ambiguous statutes, and even define the boundaries of their own jurisdiction. Agencies have greater democratic legitimacy and technical competence to confront many issues than lawyers and judges do. And as the questions confronting the state involving climate change, terrorism, and biotechnology (to name a few) have become ever more complex, legal logic increasingly indicates that abnegation is the wisest course of action. As Law’s Abnegation makes clear, the state did not shove law out of the way. The judiciary voluntarily relegated itself to the margins of power. The last and greatest triumph of legalism was to depose itself.

This book, first published in 2002, compiles psychologists' best attempts to answer important questions about intuitive judgment.

A distinguished and experienced appellate court judge, Richard A. Posner offers in this new book a unique and, to orthodox legal thinkers, a startling perspective on how judges and justices decide cases. When conventional legal materials enable judges to ascertain the true facts of a case and apply clear pre-existing legal rules to them, Posner argues, they do so straightforwardly; that is the domain of legalist reasoning. However, in non-routine cases, the conventional materials run out and judges are on their own, navigating uncharted seas with equipment consisting of experience, emotions, and often unconscious beliefs. In doing so, they take on a legislative role, though one that is confined by internal and external constraints, such as professional ethics, opinions of respected colleagues, and limitations imposed by other branches of government on freewheeling judicial discretion. Occasional legislators, judges are motivated by political considerations in a broad and sometimes a narrow sense of that term. In that open area, most American judges are legal pragmatists. Legal pragmatism is forward-looking and policy-based. It focuses on the consequences of a decision in both the short and the long term, rather than on its antecedent logic. Legal pragmatism so understood is really just a form of ordinary practical reasoning, rather than some special kind of legal reasoning. Supreme Court justices are uniquely free from the constraints on ordinary judges and uniquely tempted to engage in legislative forms of adjudication. More than any other court, the Supreme Court is best understood as a political court.