Justice Is Less Blind, and Less Legalistic, than We Thought: Evidence from an Experiment with Real Judges

We experimentally investigate the determinants of judicial decisions in a setting resembling real-world judicial decision making. We gave US federal judges 55 minutes to adjudicate a real appeals case from an international tribunal, with minor modifications to accommodate the experimental treatments. The fictitious briefs focused on one easily understandable issue of law. Our 2 × 2 between-subject factorial design crossed a weak precedent and legally irrelevant defendant characteristics.

In a survey, law professors predicted that the precedent would have a stronger effect than the defendant characteristics. In actuality, the precedent had no detectable effect on the judges’ decisions, whereas the two defendants’ affirmance rates differed by 45 percent. Judges’ written reasons, on the other hand, did not mention defendant characteristics, focusing instead on the precedent and other legalistic and policy considerations.