Distinguishing between Custom and Law: Empirical Examples of Endogeneity in Property and First Amendment Precedents

Abstract

This Article discusses the relationship between custom and law to highlight the phenomenon of endogeneity that arises when empirically evaluating the effects of laws. An important literature evaluates the roles of laws in motivating behaviors, including investigations of whether or how laws influence customs and social norms. Traditional economic analysis, for example, posits that codified laws influence behaviors by formally incentivizing a particular action, and social norm theories assert that the laws also communicate values. Enhancing this strand of thought, an increasing number of works employing historical or empirical analyses have linked laws to broader societal changes over time. Meanwhile, a valuable discourse examines how customs may determine both de facto laws and formally enacted laws, including the court precedents that are rendered. Whether they are directly codified into a legal test or informally referenced, customs can influence formal laws that are adopted in a community and beyond. Indeed, some scholars have argued that evolving customs and norms have influenced the Supreme Court in its decisions.

The subsequent effects of these formal laws and court decisions are of tremendous interest to policymakers and judges. With policy concerns in mind, we argue that one must not ignore the endogenous feedback between aggregate behaviors, customs, and laws. That is, while customs may shape or influence laws, laws can also shape customs through their effects on behaviors or norms in the aggregate. The endogeneity that custom produces suggests that simply by observing a correlation between law and behavior is not enough to assert that a law in itself is effective or to assert that social trends and evolving customs are driving legal change.

Keywords: law, customs, social norms