Legal Determinacy and Moral Justification

The idea that legal theories seek not only to explain but to evaluate the moral justification of particular areas of law is quite familiar. Yet little attention has been paid to the minimal criteria of adequacy for justificatory legal theories. Whereas many theories claim to identify the moral grounds that justify a particular area of law, such as contracts or torts, none of them explains how its justification determines the outcomes of adjudication governed by the law in that area. In this brief Essay for the William and Mary Law Review Symposium on Law and Morality, I argue that a particular area of law can be justified only by identifying moral reasons that fully determine the results of adjudication. No matter how compelling the moral reasons a legal theory identifies, and how tight the fit between those reasons and the structure and content of the legal rules governing a judicial decision, a legal theory fails to justify a particular area of law if the reasoning it identifies falls short of fully determining the results in the judicial decisions governed by that law. Though this bold claim may seem unrealistic, I argue that legal theories can satisfy this determinacy requirement by identifying determinate but inconclusive reasoning that explains outcomes in adjudication. While such reasoning may prove to be erroneous, that does not undermine its justificatory force