Does Legal Doctrine Matter? Unpacking Law and Policy Preferences on the U.S. Supreme Court

Abstract

Judicial scholars often struggle to disentangle the effects of law and policy preferences on U.S. Supreme Court decision making. We employ a new approach to measuring the effect—if any—of the law on justices' decisions. We use positions taken on Supreme Court cases by members of Congress and presidents to identify policy components of voting. Doing so enables us to isolate the effects of three legal doctrines: adherence to precedent, judicial restraint, and a strict interpretation of the First Amendment's protection of speech clause. We find considerable evidence that legal factors play an important role in Supreme Court decision making. We also find that the effect of legal factors varies across justices.