Discovering the Logic of Legal Reasoning

The rule of law rests on the quality of legal reasoning. The rule of law requires that similar cases should be decided similarly, that each case should be decided on its merits, and that decision-making processes should comply with applicable rules of procedure and evidence. Making the reasoning behind such decision-making transparent and open to scrutiny shifts the decisions away from mere subjective preference and toward objective rationale. An important means, therefore, of achieving the rule of law is articulating and evaluating the various elements of legal reasoning—the reasoning involved in interpreting constitutions, statutes, and regulations, in balancing fundamental principles and policies, in adopting and modifying legal rules, in applying those rules to cases, in evaluating evidence, and in making ultimate decisions. Despite our need for transparent and sound reasoning, we in the legal profession devote surprisingly little research to developing our own general methodology. This is in dramatic contrast to other fields and professions. We are not like mathematicians, whose reflection on their own method has given the world axiomatic proof and modern deductive logic. We are also unlike statisticians, who have developed the analytic methods in use in all areas of empirical research. Nor do we act like natural and social scientists, who carefully combine statistical methods with techniques for measurement and modeling that are tailored to their particular subject matters. Nor do we take the approach of the medical profession, which has refined various methodologies for diagnostic reasoning. We in the legal profession largely content ourselves with “knowing good legal reasoning when we see it.” We spend relatively