Judicial Conflicts and Voting Agreement: Evidence from Interruptions at Oral Argument

This Article asks whether observable conflicts between Supreme Court justices—interruptions between the justices during oral arguments—can predict breakdowns in voting outcomes that occur months later. To answer this question, we built a unique dataset based on the transcripts of Supreme Court oral arguments and justice votes in cases from 1960 to 2015. We find that on average a judicial pair is seven percent less likely to vote together in a case for each interruption that occurs between them in the oral argument for that case. While a conflict between the justices that leads to both interruptions and a breakdown in the voting coalition is one possible explanation of the finding, it is not the only one. An interruption by one justice of another justice could instead just reflect something about the case that renders it more prone to disagreement, such as being legally or politically salient, or something more idio-syncratic about the way the individual interrupting justice views the case. We set out an empirical strategy that isolates the conflict explanation from these and other possible explanations and find that the conflict inherent in interruptions explains over half of the relationship between interruptions and disagreement. These findings suggest that oral arguments are important in shaping judicial decisions—they are not simply a “dog and pony show”—and that there is valuable information about future case outcomes that has not previously been appreciated.