Who Controls Opinion Content? Testing Theories of Authorship using Case-Specific Preference Estimates for the US Supreme Court∗

Recent research has demonstrated that the preferences of US Supreme Court justices are not simply unidimensional. We demonstrate a new approach to Bayesian preference estimation that estimates case-specific preferences for justices, using a conditional autoregressive model with citation counts determining the correlation between justices’ preferences across cases. By using citations between cases to identify the most relevant precedent cases, we are able to describe variation in revealed preferences across areas of the law. In applications that test theories of bargaining on the Court, these estimates enable stronger identification of variation in preferences while holding the composition of the Court constant. We show that Chief Justices from 1946 to 2005 strategically assign authorship to their colleagues in cases where those colleagues are more closely in agreement with the Chief Justice, and patterns of other justices joining those opinions are consistent with the idea that authors shape the content of opinions. ∗We thank Andrew Martin and Maya Sen for helpful comments and suggestions. Earlier versions of this paper were presented at the 2013 meetings of the European Political Science Association and the American Political Science Association, the Princeton University Public Law Colloquium, and at Emory University.