Sahar Abi-Hassan, Janet M. Box-Steffensmeier, Dino P. Christenson, Aaron R. Kaufman, and Brian Libgober.
Interest group influence is pervasive in American politics, impacting the function of every branch. Core to the study of interest groups, both theoretically and empirically, is the ideology of the group, yet relatively little is known on this front for the vast expanse of them. By leveraging ideal point estimation and network science, we provide a novel measure of interest group ideology for over 13,000 unique groups across almost 100 years, which provides the largest and longest measure of interest group ideologies to date. We make methodological and measurement contributions using exact matching and hand-validated fuzzy string matching to identify amicus curiae signing organizations who have given political donations and then impute and cross-validate ideal points for the organizations based on the network structure of amicus cosigning. Our empirical investigation provides insights into the dynamics of interest group macro-ideology, ideological issue domains in the Court and ideological differences between donor and non-donor organizations.