Case selection and Supreme Court pivots

How does the Rule of Four affect Supreme Court decisions? We show two effects of changing a “hearing pivot” justice who is decisive for case selection. First, a court with more extreme hearing pivots will hear cases with more moderate precedents. For example, as the conservative hearing pivot becomes more extreme, the court hears a broader range of cases with liberal status quo precedents. Second, more extreme hearing pivots shrink dispositional majorities and lead to more polarized rulings. If the median justice becomes more extreme without changing the hearing pivots, then rulings are more extreme. The effect on the range of cases heard, however, is smaller than that from changing hearing pivots. Finally, we show that case selection can also depend on non-median, non-hearing-pivot justices. Replacing an extreme justice with someone even more extreme can lead to a smaller set of heard cases, as final rulings can shift away from the binding hearing pivot, making status quo precedents more appealing.

Case Selection and Supreme Court Pivots

How does the Rule of Four affect Supreme Court decisions? We show two effects of changing a ``hearing pivot" justice who is decisive for case selection. First, as this justice becomes more extreme, the court hears a larger set of policies. That is, as the hearing pivot becomes more conservative, the court hears more cases with liberal status quo precedents. Second, as the hearing pivot becomes more extreme, dispositional majorities shrink and rulings are more polarized. When the median justice becomes more extreme without changing the hearing pivot, rulings become more extreme as the majority opinion shifts. Yet, the set of cases heard changes very little. Finally, we show that changing non-pivotal justices also affects case selection. If an extreme justice is replaced with someone even more extreme, this may expand the gridlock interval. Extreme justices pull the bargaining policy away from the hearing pivot, thus making status quo precedents more appealing.

Are Supreme Court Nominations a Move-the-Median Game?

We conduct a theoretical and empirical re-evaluation of move-the-median (MTM) models of Supreme Court nominations—the one theory of appointment politics that connects presidential selection and senatorial confirmation decisions. We develop a theoretical framework that encompasses the major extant models, formalizing the tradeoff between concerns about the location of the new median justice versus concerns about the ideology of the nominee herself. We then use advances in measurement and scaling to place presidents, senators, justices, and nominees on the same scale, allowing us to test predictions that hold across all model variants. We find very little support for MTM theory. Senators have been much more accommodating of the president’s nominees than MTM theory would suggest—many have been confirmed when the theory predicted they should have been rejected. These errors have been consequential: presidents have selected many nominees who are much more extreme than MTM theory would predict. These results raise serious questions about the adequacy of MTM theory for explaining confirmation politics and have important implications for assessing the ideological composition of the Court.

The Supreme Court's Many Median Justices

One-dimensional spatial models have come to inform much theorizing and research on the U.S. Supreme Court. However, we argue that judicial preferences vary considerably across areas of the law, and that limitations in our ability to measure those preferences have constrained the set of questions scholars pursue. We introduce a new approach, which makes use of information about substantive similarity among cases, to estimate judicial preferences that vary across substantive legal issues and over time. We show that a model allowing preferences to vary over substantive issues as well as over time is a significantly better predictor of judicial behavior than one that only allows preferences to vary over time. We find that judicial preferences are not reducible to simple left-right ideology and, as a consequence, there is substantial variation in the identity of the median justice across areas of the law during all periods of the modern court. These results suggest a need to reconsider empirical and theoretical research that hinges on the existence of a single pivotal median justice.