Experimental Justice: Random Judicial Assignment and the Partisan Process of Supreme Court Review

This study utilizes the random assignment of judges to panels in the U.S. courts of appeals to measure how the partisanship of these judges affects whether or not the Supreme Court agrees to hear a case and subsequently overturns the decision of the lower panel. Results from the study provide evidence of partisan behavior in the Supreme Court review process in several politically salient issue areas between 1995 and 2004. Although most lower court decisions are never reviewed at all, in the cases examined, assigning three Democrats to a court of appeals panel, compared to three Republicans, more than quintupled the chances that the Supreme Court would overturn a decision from that panel. Despite the large magnitude of these effects, the estimates of partisan effects would have been even larger without the utilization of random assignment.