Legal constraints on Supreme Court decision making: Do jurisprudential regimes exist

The founding debate of judicial politics—is Supreme Court decision making driven by law or politics? —remains at center stage. One influential line of attack involves the identification of jurisprudential regimes, stable patterns of case decisions based on the influence of case factors. The key test is whether the regime changes after a major precedent-setting decision, that is, whether the case factors are subsequently treated differently by the Supreme Court justices themselves so that they vote as though constrained by precedent. We analyze whether binding jurisprudential regime change actually exists. The standard test assumes votes are independent observations, even though they are clustered by case and by term. We argue that a (nonparametric) ‘‘randomization test’ ’ is more appropriate. We find little evidence that precedents affect voting. T he founding debate of judicial politics—is Supreme Court decision making driven by law or politics? —remains at center stage today. In the first half of the twentieth century, the realist move-ment stressed the role of personal choice in judging. Now, a common view in political science, that of Spaeth and Segal (1999) and Segal and Spaeth (2002), is even more extreme: law has little or no influence over the case votes of Supreme Court Justices. Richards and Kritzer (2002) pioneered a bold challenge to this view, arguing that law does affect these votes, that justices do make decisions as though bound by law. Their claim is that this influence can be detected by studying ‘‘jurisprudential regimes,’ ’ stable patterns of case decisions in a given area before and after key precedents are established. That Supreme Court decisions affect the decisions of lower court judges (vertical stare decisis) is not controversial. Their argument, however, goes much further. They argue that precedent effectively constrains the justices them-selves (horizontal stare decisis), that key precedents induce new jurisprudential regimes in Supreme Court decision making. In short, they find that law can trump politics even in the Supreme Court. Applying this clever research design, Kritzer and Richards present evidence that key precedents have caused jurisprudential regime change in four area