Reviewed in this post: Pamela C. Corley, Amy Steigerwalt, and Artemus Ward, The Puzzle of Unanimity: Consensus on the United States Supreme Court (Stanford University Press, 2013)
Many of the most notable recent Supreme Court decisions have been sharply divided affairs, usually involving predictable configurations of conservative and liberal justices glaring across a vast chasm of ideological differences. The majority and dissenting opinions in cases such as last term’s decisions on the Voting Rights Act and the Defense of Marriage Act reflect such fundamentally opposing judicial worldviews that it can be hard to imagine their authors agreeing on much of anything of importance. Yet these 5-4 decisions, which capture the attention of the public and scholars alike, reflect only a fraction of the docket of the nation’s highest court. As the justices often remind audiences when writing or speaking about their work, they actually agree with each other quite often. Approximately one-third of all decided cases in recent terms have been unanimous. If we add those decisions in which only a single justice dissented, we find a majority of cases in recent terms have been either unanimous or nearly unanimous. Why does this happen? How can a court that is so polarized on many of the most foundational legal and constitutional questions come together with such regularity? This is the question explored by political scientists Pamela C. Corley, Amy Steigerwalt, and Artemus Ward in The Puzzle of Unanimity: Consensus on the United States Supreme Court.
The answer they provide to this motivating question is intuitively persuasive, if perhaps rather anticlimactic. Their answer, in a nutshell: it is complicated. Explaining the prevalence of unanimous and near-unanimous decisions requires attention to numerous factors—the ideology of the justices, strategic considerations, and constraints of law and legal norms, among them—with certain factors playing more or less of a role in different circumstances. “Rather than single out a specific group of factors as the primary explanation for consensus, we argue that various potential influences all operate in each case and many times, in complex interactive fashion” (p. 6). (more…)