Of time and consensual norms in the Supreme Court

Theory: We argue that levels of concurrence and dissent on the U.S. Supreme Court are functions of "consensual norms." These norms arise from, and are influenced by, the behaviors of the individual justices, including the actions of the chief justices. In turn, they cause concurrences and dissents to fluctuate around a common level. Hypotheses: If consensual norms are a substantial influence on the behavior of the Court, the long-run extent of concurrence and dissent on the Court will covary substantially, and will do so to varying degrees under different chief justices. Methods: To test our hypotheses, we use cointegration and error-correction analyses of the number of Supreme Court cases from 1800 to 1991 with concurring and dissenting opinions. Because of the dramatic increase in concurrences and dissents during the 1940s, we make use of recently-developed methods for detecting cointegrating relationships in the presence of structural breaks. Results: Consistent with our expectations, dissents and concurrences move together over time; thus consensual norms appear to influence substantially both concurrences and dissents on the Court. The effects of such norms vary in the long term under different Chief Justices.