We can observe and measure how legal decision makers use formal legal authorities, but there is no way to empirically test the determinative capacity of legal doctrine itself. Yet, discussions of empirical studies of judicial behavior sometimes conflate judges’ attention legal rules with legal rules determining outcomes. Doctrinal determinacy is not the same thing as legal predictability. The extent to which legal outcomes are predictable in given contexts is surely testable empirically. But the idea that doctrine’s capacity to produce or limit those outcomes can be measured empirically is fundamentally misguided. The problem is that to measure doctrinal determinacy, we would have to adopt standards of legal correctness that violate fundamental conceptual and normative aspects of the legal institution we wish to study. In practice the promise of empirical data on doctrinal determinacy makes it seem less urgent to investigate other contributions doctrinal reasoning makes to law. Doctrinal reasoning might affect decision makers in ways that contribute importantly to legal process without determining outcomes. Trying to understand those effects is a research project to which the empirical methods of social science have much to contribute.
Allen, Jessie, Empirical Doctrine (August 28, 2015). Case Western Reserve Law Review, Fall 2015, forthcoming; U of Pittsburgh Legal Studies Research Paper No 2015-31.