Published in 2007 in the Journal of Law, Economics, & Organization 23: 303-325.

Revised version of papers delivered at the 2005 Conference on Law and Positive Political Theory, Northwestern University School of Law and the 2005 annual meeting of the Law & Society Association, Las Vegas NV.

Lee Epstein
Andrew D. Martin
Jeffrey A. Segal
Chad Westerland

Assessing the empirical implications of many theoretical models of judicial politics requires a measurement strategy for placing relevant actors (judges of lower courts, justices of the Supreme Court, members of Congress, and the President) in the same policy space.

We take up this challenge in three steps. We begin by explicating our measurement strategy, and then by explaining its advantages over previous efforts. Next we explore the results of our approach, and provide a descriptive look at data it yields: a ``Judicial Common Space" score for all justices and judges serving between 1953 and 2006. The last section offers three contemporary applications---all of which, we hope, shore up the suitability and adaptability of the Judicial Common Space for research on law and courts.

Click here for the article (.pdf).
Click here for the data (zipped Stata 10 .dta files) or here (Stata 9.dta files) Recent updates: (1) May 28, 2010. This update corrects an error in the JCS median file: the median for year 1, 105th Congress was incorrect. We thank Anna Harvey for pointing out this error. (2) July 23, 2010. We corrected misspellings in the names of two judges. We thank Rafael Pardo for the corrections.