The Role of Ideology in Judicial Evaluations of Experts

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I provide a test of the legal realist theory of judicial behavior, which posits that judges’ ideology impacts their legal decisions but that the law constrains the judges’ ability to exercise those preferences. Two competing theories, legal skepticism and formalism, posit that the law either provides a minimal constraint on judges’ preferences or allows only minimal discretion by judges. The difficulty in testing these theories is a lack of data on the legal constraints judges face. I examine Daubert/Rule 702 rulings to exclude scientific testimony by plaintiffs’ experts in a series of lawsuits. Because I have multiple observations across experts, I can give each expert a fixed effect, which removes any constant features of the expert’s testimony. Even after controlling for law, I find robust evidence that ideology plays an important role in the decision to grant a motion to exclude a witness.

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