Empirical studies have examined the effects of law and politics on judicial decision-making, but many legal scholars are dissatisfied with how these studies account for law. This paper provides a novel survey technique for measuring law. I demonstrate this technique by examining judicial decision-making in cases involving the single subject rule. The rule limits ballot propositions to one “subject,” a standard that vests judges with some discretion. Measures of law developed with the surveys strongly predict judges’ votes in single subject cases. Moving from the proposition in the sample with the lowest subject count to the one with the highest is associated with a 78 percentage point increase in the likelihood of a judge finding a violation of the rule. Measures of ideology also predict judges’ votes, especially when propositions are politically salient and when the law is indeterminate.
Michael D. Gilbert, Does Law Matter? Theory and Evidence from Single Subject Adjudication, 40 Journal of Legal Studies 333–365 (2011).