Dimensionality on the Supreme Court

Estimates of the ideological preferences of Supreme Court justices play a major role in the study of the court. This paper considers the dimensionality of these preferences. First, we consider unstructured approaches to multidimensionality, showing that the second dimension they produce is hard to explain and unstable over time. We then move toward a concept-driven approach to account for possible multidimensionality. This approach allows one to test whether concepts such as stare decisis lead justices to deviate from their one-dimensional left-right ideologies. This approach can help explain important outcomes on the court, although less so in recent years.