In twenty-five different experiments conducted on over 2,200 judges, we assessed whether judges' political ideology influences their resolution of hypothetical cases. Generally, we found that the political ideology of the judge matters, but only very little. Across a range of bankruptcy, criminal, and civil cases, we found that the aggregate effect of political ideology is either nonexistent or amounts to roughly one quarter of a standard deviation. Overall, the results of our experiments suggest that judges are not "politicians in robes."
Jeffrey J. Rachlinski, Andrew J. Wistrich, and Chris Guthrie,
Judicial Politics and Decisionmaking: A New Approach,
70 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vlr/vol70/iss6/16