Published · International Review of Law and Economics
The Cognitive Underpinnings of Judicial Bias: The Role of Social Identity and Prospect Theory
Abstract and paper
Under what conditions do judges favor their own group? Collecting the available universe of Superior Court decisions in Kenya, we leverage the random assignment of cases to judges to evaluate the extent of judicial in-group bias along gender and ethnic lines. We find that defendants are 4 or 6 percentage points more likely to win if they share the judge’s gender or ethnicity, respectively, and that judges are significantly more biased in favor of defendants than plaintiffs. Our findings highlight the need to re-examine the emerging consensus that judges uniformly favor their own group and continue investigating the mechanisms driving judicial bias. We propose that the uneven application of bias can be explained by a framework of social identity and loss aversion, and we support this claim with data on the amount of damages in each case, which we extract using a large language model. Finally, we argue that our framework could serve as a more complete lens through which to decipher the cognitive underpinnings of judicial biases.