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The Ideologies of Organized Interests and Amicus Curiae Briefs: Large-Scale, Social Network Imputation of Ideal Points

Published online by Cambridge University Press:  26 January 2023

Sahar Abi-Hassan
Assistant Professor, Kathryn P. Hannam Professor of American Studies, Department of Public Policy and Political Science, Mills College, Oakland, CA, USA. E-mail:
Janet M. Box-Steffensmeier
Vernal Riffe Professor of Political Science and Sociology, The Ohio State University, Columbus, USA. E-mail:
Dino P. Christenson*
Associate Professor, Department of Political Science, Washington University in St. Louis, St. Louis, USA. E-mail:
Aaron R. Kaufman
Assistant Professor, Division of Social Sciences, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates. E-mail:
Brian Libgober
Assistant Professor, School of Global Policy and Strategy, UC San Diego, San Diego, USA. E-mail:
Corresponding author Dino P. Christenson


Interest group ideology is theoretically and empirically critical in the study of American politics, yet our measurement of this key concept is lacking both in scope and time. By leveraging network science and ideal point estimation, we provide a novel measure of ideology for amicus curiae briefs and organized interests with accompanying uncertainty estimates. Our Amicus Curiae Network scores cover more than 12,000 unique groups and more than 11,000 briefs across 95 years, providing the largest and longest measure of organized interest ideologies to date. Substantively, the scores reveal that: interests before the Court are ideologically polarized, despite variance in their coalition strategies; interests that donate to campaigns are more conservative and balanced than those that do not; and amicus curiae briefs were more common from liberal organizations until the 1980s, with ideological representation virtually balanced since then.

© The Author(s), 2023. Published by Cambridge University Press on behalf of the Society for Political Methodology

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Edited by Daniel Hopkins


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