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The Supreme Court's Many Median Justices

Published online by Cambridge University Press:  09 November 2012

London School of Economics and Political Science
Emory University
Benjamin E. Lauderdale is Lecturer, Department of Methodology, London School of Economics and Political Science, Columbia House, Houghton Street, London, UKWC2A 2AE (
Tom S. Clark is Associate Professor, Department of Political Science, Emory University, 327 Tarbutton Hall, 1555 Dickey Drive, Atlanta, GA 30322 (


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.

Research Article
Copyright © American Political Science Association 2012

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Alfano, Sean. 2009. “The Kennedy Court.” (accessed August 3, 2012).Google Scholar
Bailey, Michael A. 2007. “Comparable Preference Estimates across Time and Institutions for the Court, Congress, and Presidency.” American Journal of Political Science 51 (3): 433–48.CrossRefGoogle Scholar
Baird, Vanessa A. 2007. Answering the Call of the Court: How Justices and Litigants Set the Supreme Court Agenda. Charlottesville: University of Virginia Press.Google Scholar
Bonica, Adam. 2010. A Day by Day Measure of Legislator Ideology, Ph.D. thesis. New York University.Google Scholar
Caldeira, Gregory A., and Wright, John R.. 1998. “Lobbying for Justice: Organized Interests, Supreme Court Nominations, and the United States Senate.” American Journal of Political Science 42 (2): 499523.CrossRefGoogle Scholar
Cameron, Charles M., Cover, Albert D., and Segal, Jeffrey A.. 1990. “Senate Voting on Supreme Court Nominees: A Neoinstitutionalist Model.” American Political Science Review 84 (2): 525–34.CrossRefGoogle Scholar
Clark, Tom S., and Lauderdale, Benjamin. 2010. “Locating Supreme Court Opinions in Doctrine Space.” American Journal of Political Science 54 (4): 871–90.CrossRefGoogle Scholar
Clinton, Joshua D., and Meirowitz, Adam. 2003. “Integrating Roll Call Analysis and Voting Theory: A Framework.” Political Analysis 11: 381–96.CrossRefGoogle Scholar
Clinton, Joshua D., Jackman, Simon, and Rivers, Douglas. 2004. “The Statistical Analysis of Roll Call Data.” American Political Science Review 98 (2): 355–70.CrossRefGoogle Scholar
Cole, David. 2006. “The ‘Kennedy Court’.” The Nation, July 31.Google Scholar
deFigueiredo, John M. 2005. “Strategic Plaintiffs and Ideological Judges in Telecommunications Litigation.” Journal of Law, Economics and Organization 21 (2): 501–23.CrossRefGoogle Scholar
Eddelbuettel, Dirk, and François, Romain. 2011. “Rcpp: Seamless R and C++ Integration.” Journal of Statistical Software 40 (8): 118. (accessed August 3, 2012).CrossRefGoogle Scholar
Greenhouse, Linda. 2005. Becoming Justice Blackmun: Harry Blackmun's Supreme Court Journey. New York: Times Books.Google Scholar
Greenhouse, Linda. 2010. “Is the ‘Kennedy Court’ Over?” (accessed August 3, 2012).Google Scholar
Grofman, Bernard, and Brazill, Timothy J.. 2002. “Identifying the Median Justice on the Supreme Court through Multidimensional Scaling: Analysis of “Natural Courts “1953–1991.” Public Choice 112 (1/2): 5579.CrossRefGoogle Scholar
Ho, Daniel E., and Quinn, Kevin M.. 2010. “How Not to Lie with Judicial Votes: Misconceptions, Measurement, and Models.” California Law Review 98 (3): 813–76.Google Scholar
Jessee, Stephen. 2009. “Spatial Voting in the 2004 Presidential Election.” American Political Science Review 103: 5981.CrossRefGoogle Scholar
Kastellec, Jonathan P., Lax, Jeffrey R., and Phillips, Justin H.. 2010. “Public Opinion and Senate Confirmation of Supreme Court Nominees.” Journal of Politics 72 (3): 767–84.CrossRefGoogle Scholar
Krehbiel, Keith. 2007. “Supreme Court Appointments as a Move-the-Median Game.” American Journal of Political Science 51 (2): 231–40.CrossRefGoogle Scholar
Lane, Charles. 2006. “Kennedy Reigns Supreme on Court.” Washington Post, July 2.Google Scholar
Lax, Jeffrey R. 2007. “Constructing Legal Rules on Appellate Courts.” American Political Science Review 101 (3): 591604.CrossRefGoogle Scholar
Lax, Jeffrey R. 2011. “The New Judicial Politics of Legal Doctrine.” Annual Review of Political Science 14: 131–57.CrossRefGoogle Scholar
Lithwick, Dahlia. 2006. “Swing Time.” (accessed August 3, 2012).Google Scholar
Londregan, John. 2000. “Estimating Legislators’ Preferred Points.” Political Analysis 8 (1): 3556.CrossRefGoogle Scholar
Martin, Andrew D., and Quinn, Kevin M.. 2002. “Dynamic Ideal Point Estimation via Markov Chain Monte Carlo for the U.S. Supreme Court, 1953–1999.” Political Analysis 10: 134–53.CrossRefGoogle Scholar
Moraski, Byron J., and Shipan, Charles R.. 1999. “The Politics of Supreme Court Nominations: A Theory of Institutional Constraints and Choices.” American Journal of Political Science 43 (4): 1069–95.CrossRefGoogle Scholar
Newman, Roger K. 1997. Hugo Black: A Biography. New York: Fordham University Press.Google Scholar
Peress, Michael. 2009. “Small Chamber Ideal Point Estimation.” Political Analysis 17: 276–90.CrossRefGoogle Scholar
Poole, Keith T. 2000. “Nonparametric Unfolding of Binary Choice Data.” Political Analysis 8 (2): 211–37.CrossRefGoogle Scholar
Poole, Keith T. 2005. Spatial Models of Parliamentary Voting. Cambridge: Cambridge University Press.CrossRefGoogle Scholar
Poole, Keith T., and Rosenthal, Howard. 1997. Congress: A Political-Economic History of Roll Call Voting. New York: Oxford University Press.Google Scholar
R Development Core Team. 2008. R: A Language and Environment for Statistical Computing. Vienna, Austria: R Foundation for Statistical Computing.Google Scholar
Segal, Jeffrey A. and Spaeth, Harold J.. 2002. The Supreme Court and the Attitudinal Model Revisited. Cambridge: Cambridge University Press.CrossRefGoogle Scholar
Spaeth, Harold, Epstein, Lee, Ruger, Ted, Whittington, Keith, Segal, Jeffrey, and Martin, Andrew D.. 2010. “The Supreme Court Database.” (accessed August 23, 2010).Google Scholar
Spriggs, James F. II, and Hansford, Thomas G.. 2002. “The U.S. Supreme Court's Incorporation and Interpretation of Precedent.” Law and Society Review 32 (1): 139–59.CrossRefGoogle Scholar
Stephenson, Karen, and Zelen, Marvin. 1989. “Rethinking Centrality: Methods and Examples.” Social Networks 11: 137.CrossRefGoogle Scholar
Tahk, Alexander M. 2006. “A New Approach to Optimal Classification.” Presented at the Annual Meeting of the American Political Science Association, Philadelphia.Google Scholar
Wasserman, Larry. 2005. All of Nonparametric Statistics. New York: Springer.Google Scholar
Whittington, Keith E. 2005. “The Burger Court, 1969-1986: Once More in Transition.” In The United States Supreme Court: The Pursuit of Justice, ed. Tomlins, Christopher. Boston: Houghton Mifflin, 300–22.Google Scholar
Yates, Jeff L., and Coggins, Elizabeth. 2009. “The Intersection of Judicial Attitudes and Litigant Seleciton Theories: Explaining U.S. Supreme Court Decision Making.” Washington University Journal of Law and Policy 29 (1): 263–99.Google Scholar
Zucco, Cesar Jr., and Lauderdale, Benjamin E.. 2011. “Distinguishing Between Influences on Brazilian Legislative Behavior.” Legislative Studies Quarterly 36 (3): 363–96.CrossRefGoogle Scholar
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