Rational Judicial Behavior: A Statistical Study

This paper analyzes the connection between ideology and voting of judges using a large sample of court of appeals cases decided since 1925 and Supreme Court cases decided since 1937. The ideological classifications of votes (e.g., liberal or conservative) are dependent variables in our empirical analysis and the independent variables include the party of the appointing President, the relative number of Republican and Democratic Senators at the time of the judge‘s confirmation, the appointment year, characteristics of the judge (e.g., gender, race and prior experience), and the ideological make-up of the judges on the court in which the judge sits as measured by the relative number of judges appointed by Republican and Democratic Presidents. We have a number of interesting results, including how a judge‘s voting‘s is affected by the voting of the other judges he serves with. We find a political-polarization effect among Justices appointed by Democratic but not by Republican Presidents; that is, the fewer the judges appointed by Democratic Presidents, the more liberally they vote. With regard to court of appeals judges, we find a conformity effect: if the number of judges appointed by Republican Presidents increases (decreases) relative to the number appointed by Democratic Presidents, all judges in the circuit tend to vote more conservatively (more liberally).