some judicial decisions, those factors actually explain very little of the variation in judicial outcomes. Thus, although judicial ideology has a role in filling the gaps in legal reasoning, it does not supplant the role of legal reasoning. This finding itself is probably not very surprising to most realistic observers of the courts. Few would be shocked that Democratic and Republican appointees differ systematically in their behavior on the bench. At the same time, even the most devout legal realists probably realize they would need more than to share a political party with the judge to win their case. As a result, studies that merely point out the influence of extra-legal factors in judicial decision-making often don’t shed much light on the working of the federal judiciary. The real question is how ideology integrates with the legal institutions that indisputably channel and constrain judicial behavior. The fact that ideology matters means that you can estimate the extent to which the relative ideology of different judges drives decisions. The fact that the law matters, however, means that you can evaluate judges according to a fixed reference point, unlike ideology, which is necessarily relative. This basic finding—that both law and ideology matter in judicial decisionmaking—has been the starting point for my own research on federal courts. I have sought to investigate how legal rules and doctrines constrain, channel, and influence the role of ideology in the federal courts. In one paper, I address the way in which Supreme Court justices’ opinion-writing conventions influence the ideological outcome of the case (“Institutions and Equilibrium in the United States Supreme Court,” American Political Science Review). In another paper, I address how the standards of review—the deference appellate courts give to trial courts—interact with ideology in the U.S. Court of Appeals. In both papers, my perspective is that law and procedure do constrain and channel the decisions of federal judges, even at the Supreme Court level where that constraint is most attenuated.
If judging were driven exclusively by ideology, there would be little point to ranking judges. A researcher could order the judges from left to right, but there would be no common ground that one might call “quality” In my most recent work, however, I have engaged more directly with the question of untangling judicial ideology and judicial performance. judicial “quality.” In this research, I have developed a technique for evaluating the performance of federal appellate judges according to the citations other judges make to their decisions. This technique uses the mix of positive and negative citations to evaluate the performance of federal appellate judges according to their own peers. This type of evaluation is only possible, however, if the idea of “following the law” is actually meaningful. If judging were driven exclusively by ideology, there would be little point to ranking judges. A researcher could order the judges from left to right, but there would be no common ground that one might call “quality” judicial performance. But if, as I argue, appellate judges indeed do generally “follow the law,” then empirical techniques can rank judges according to their fidelity to legal precedent. I believe my study shows that there is common ground of judicial quality and fidelity to the rule of law that federal judges both recognize and uphold in their citations. To make the analysis more concrete, my paper applied the judge-ranking technique to evaluate Judge Sonia Sotomayor as a nominee and now justice on the Supreme Court. My study revealed that Sotomayor was one of the most positively cited judges since 1960, together with other renowned judges such as Justice Stephen Breyer (then a judge on the First Circuit) and our own Dean Ken Starr (then a judge on the D.C. Circuit). Moreover, my findings 17
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