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Building a Taxonomy of Litigation: Clusters of Causes of Action in Federal Complaints


  • Christina L. Boyd,

  • David A. Hoffman,

  • Zoran Obradovic,

  • Kosta Ristovski

  • We appreciate the support for our research from the University at Buffalo's Baldy Center for Law & Social Policy and Temple University's Beasley School of Law. We also gratefully acknowledge the research assistance of Geoffrey Bauer, Keith Blackley, Matthew Canan, Antima Chakraborty, Melissa Jabour, Nicholas Mozal, Jacqueline Sievert, and Elizabeth Young and the preliminary analyses of Daniel Katz and Michael Bommarito. We received helpful comments on this project from colleagues at workshops at Temple Law School, Duke Law School, North Carolina Law School, Rutgers-Camden Law School, and the University of Georgia Department of Political Science, participants at the Midwest Political Science Association and Stanford Conference on Empirical Legal Studies 2012 annual meetings, attendees at a joint research workshop with the Federal Judicial Center and the Administrative Office of the U.S. Courts, and Joe Cecil, Dawn Chutkow, Kevin Clermont, Scott Dodson, Marc Galanter, Lonny Hoffman, William Hubbard, Greg Mandel, Morris Ratner, Paul Stancil, Rick Swedloff, Steve Subrin, and the editors and anonymous reviewers at JELS. Authors are listed in alphabetical order.

Address correspondence to Christina Boyd, University at Buffalo, SUNY, Department of Political Science, 520 Park Hall (North Campus), Buffalo, NY 14260; email: or David Hoffman, Beasley School of Law, Temple University, 1719 N. Broad St., Philadelphia, PA 19122; email:


This project empirically explores civil litigation from its inception by examining the content of civil complaints. We utilize spectral cluster analysis on a newly compiled federal district court data set of causes of action in complaints to illustrate the relationship of legal claims to one another, the broader composition of lawsuits in trial courts, and the breadth of pleading in individual complaints. Our results shed light not only on the networks of legal theories in civil litigation but also on how lawsuits are classified and the strategies that plaintiffs and their attorneys employ when commencing litigation. This approach permits us to lay the foundation for a more precise and useful taxonomy of federal litigation than has been previously available, one that, after the Supreme Court's recent decisions in Bell Atlantic v. Twombly (2007) and Ashcroft v. Iqbal (2009), has also arguably never been more relevant than it is today.