Measuring Judicial Ideology Through Text

Explorations of ideology retain special significance in contemporary studies of judicial politics. While some existing methodologies draw on voting patterns and coalition alignments to map a jurist’s latent features, many are otherwise reliant on supplemental proxies – often directly from adjacent actors or via assessments from various prognosticators. We propose an alternative that not only leverages observable judicial behavior, but does so through jurists’ articulations on the law. In particular, we adapt a hierarchical factor model to demonstrate how latent ideological preferences emerge through the written text of opinions. Relying on opinion content from Justices of the Supreme Court, we observe a discernible correlation between linguistic choices and latent expressions of ideology irrespective of known preferences or voting patterns. Testing our method against Martin-Quinn, we find our approach strongly correlates with this validated and commonly used measure of judicial ideology. We conclude by discussing the intuitive power of text as a feature of ideology, as well as how this process can extend to judicial actors and institutions beyond the Supreme Court.