Cooperation and Division: An Empirical Analysis of Voting Similarities and Differences During the Stable Rehnquist Court Era — 1994 to 2005

The Stable Rehnquist Court Era (SRCE) covers the period from the appointment of Justice Breyer to the passing of Chief Justice Rehnquist. There has been only one longer period of stability in the Court’s history, and that was in the early nineteenth century when far fewer cases were decided. Because the composition of the Court held constant for so long, the SRCE presents a unique opportunity to conduct a statistical analysis of the Justices’ votes. I present a statistical empirical analysis of voting for this period, both for the potentially interesting results and as an example of how to conduct and present an empirical study which is objective and replicable. Some of the findings include the following: only a few pairs of Justices have statistically significant differences in voting records; the magnitude of the departure from independent voting is enormous in statistical terms; Justice Thomas is the most predictable Justice; and Justice Scalia is the least-changed Justice. Of particular interest is a finding that is contrary to conventional wisdom. Conventional wisdom suggests that the median Justice closest to the center, presumably Justice Kennedy, is the most influential Justice. However, I have developed a measure of influence which employs the statistically significant effects the Justices have on each other, and this suggests that the most influential Justices on the Court during the SRCE were Rehnquist, Souter, and Breyer.