Lee Epstein
Lee Epsteing Ethan A.H. Shepley Distinguished University Professor
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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 [now through 2020]. 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 most recent data: zipped Stata (.dta) and R (.RData) files. Posted on January 5, 2021. Note: (1) files with _pence estimate the scores using Pence's nominate score (Trump's is not available) and (2) files with _sen_repub estimate the scores using the mean nominate score of the Senate's Republicans.

(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.
(3) June 10, 2015. Updated scores.
(4) July 13, 2015. This update corrects some small typos in the spelling of four judges' names and mistakes in the ideology scores of two judges on the DC Circuit (Henderson and Tatel). We thanks Christy Boyd and Micheal Giles for pointing out these errors.
(5) July 4, 2016. One correction: "Martin, Barbara" (11th circuit) should be "Martin, Beverly Baldwin." Thanks to Adam Samaha for bringing this error to our attention.
(6) October 8, 2016. One correction: "Mortiz, Nancy" (10th circuit) should be "Moritz, Nancy." Thanks to Ryan Black for spotting this typo.
(7) December 12, 2017. Siyu Li noticed that the congress number in row 62 should be 115, not 113. We have made this correction.
(8) April 26, 2018. Corrects two DC Circuit errors in the data posted on April 19, 2018.
(9) December 15, 2019. Thanks to Elizabeth Lane for noticing that 1945 should be the start of the the 79th Congress, with the Senate median at 0.0585 and the House median at -0.044.