Models and Methods Commons^™

Partisan Voting On The California Supreme Court, Mark P. Gergen, David A. Carrillo, Benjamin M. Chen, Kevin M. Quinn

Faculty Articles

When did ideology become the major fault line of the California Supreme Court? To answer this question, we use a two-parameter item response theory (IRT) model to identify voting patterns in non-unanimous decisions by California Supreme Court justices from 1910 to 2011. The model shows that voting on the court became polarized on recognizably partisan lines beginning in the mid-1900s. Justices usually did not vote in a pattern that matched their political reputations and party affiliation during the first half of the century. This began to change in the 1950s. After 1959 the dominant voting pattern is partisan and closely …