We present a new measure of judicial ideology based on judicial hiring behavior. Specifically, we utilize the ideology of the law clerks hired by federal judges to estimate the ideology of the judges themselves. These Clerk-Based Ideology (CBI) scores complement existing measures of judicial ideology in several ways. First, CBI scores can be estimated for judges across the federal judicial hierarchy. Second, CBI scores can capture temporal changes in ideology. Third, CBI scores avoid case selection and strategic behavior concerns that plague existing vote-based measures. We illustrate the promise of CBI scores through a number of applications.
Bonica, Adam, Adam Chilton, Jacob Goldin, Kyle Rozema, and Maya Sen. "Measuring Judicial Ideology Using Law Clerk Hiring." HKS Faculty Research Working Paper Series RWP16-031, July 2016.