The Role of Ideology in Judicial Evaluations of Experts

The Journal of Law and Economics, Volume 62, Number 4, pages 579–611 (November 2019). doi: 10.1086/705838

Posted on on December 11, 2020

by Eric Helland

Read More

Access further information on this document at The University of Chicago Press Journals

This article was published outside of RAND. The full text of the article can be found at the link above.

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.

Research conducted by

This report is part of the RAND Corporation External publication series. Many RAND studies are published in peer-reviewed scholarly journals, as chapters in commercial books, or as documents published by other organizations.

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.