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Joseph Scott Miller: A Citation-Network Approach to Mapping Judicial Ideology
Michael Ramsey

Joseph Scott Miller (University of Georgia School of Law) has posted “Justice X, dissenting”: A Citation-Network Approach to Mapping Judicial Ideology (54 pages) on SSRN.  Here is the abstract:

Appellate judges prefer some outcomes over others. We can tell because we see them disagree with one another regularly, both within a given a case and across a run of cases. Scholars, both in political science and law, have used various techniques to quantify judges’ policy preferences and chart those preferences, both across judge and through time. The Martin-Quinn score is a prominent example. But appellate judges don’t simply vote. They also write, justifying their judgments. When writing for a majority, the authoring judge must accommodate her partners in the majority, dropping or adding text (including citations) to keep the majority together. When writing a dissent or concurrence, by contrast, the judge can write simply to explain, without accommodation, how she views the issues in the case. Indeed, given that dissenting or concurring triggers varied costs, the chance to justify one’s analysis without compromise is perhaps the main benefit to writing a dissent or concurrence at all. Can we map an appellate judge’s ideological preferences in a way that harnesses the information these separate opinions provide? Citation network analysis is a promising way to do so. In this project, I gather the citation data (to earlier Supreme Court opinions) from all of Justice Scalia’s and Justice Thomas’s dissenting and concurring opinions on the Supreme Court, through the end of the October 2019 Term in July 2020, and then measure and map the resulting citation and co-citation networks, across all opinions and parsing concurrences from dissents. Justices Scalia and Thomas are an especially apt pair of justices to study in this way for three reasons: (a) as of 2020 they served for a similar period of years; (b) they have both dissented and concurred at similarly high rates, generating rich citation networks; and (c) they were each one another’s closest ideological fellow-traveler using scores like M-Q , making any differences between them revealed by citation-network analysis that much more informative. In summary: Justice Scalia sought mainly to reshape judicial power. Justice Thomas, by contrast, has sought mainly to reshape legislative power, including by enhancing state legislative power.