judicial_common_space

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What is judicial_common_space?

judicial_common_space computes the Judicial Common Space (JCS) score of every appointment of a federal judge who has served since 1953 (the first year of the original study, or any year you choose), following Epstein, Martin, Segal, and Westerland, "The Judicial Common Space," 23 J.L. Econ. & Org. 303 (2007). It saves them in a spreadsheet with each judge's name, the Federal Judicial Center's two numbers for the judge (nid and jid), and the judge's score for each appointment, and checks them against the published scores.

Why use judicial_common_space?

This package:

• Scores every Article III appointment: district courts, courts of appeals, and the Supreme Court.
• Uses the current sources, downloaded when needed: the Federal Judicial Center's Biographical Directory of Article III Federal Judges, Voteview's DW-NOMINATE scores, the congress-legislators dates of senators' service, the Martin-Quinn scores, and Wikipedia's articles on the courts of appeals (for circuit judges' duty stations).
• Shows its work: each row says which state the judge was appointed from, how that was found, and which senators (or the president) the score came from.
• Checks itself against the published JCS scores of circuit judges and justices and against Christina Boyd's scores of district judges, which are made the same way.

How the scores are made

The paper scores the lower courts by the rule of Giles, Hettinger, and Peppers (2001), which follows the norm of senatorial courtesy. If a judge is appointed from a state where the president and at least one senator are of the same party, the judge gets that senator's NOMINATE score, or the mean of the senators' scores. Otherwise the judge gets the president's score. Justices get their Martin-Quinn score in each term, put on the same scale by the paper's arctangent transformation: 2/π · arctan(b0 + b1 · MQ).

The package applies the rule this way:

How well they match the published scores

With the default settings, against the JCS 2024 release and Boyd's district court scores (through the 118th Congress):

With --senators date, the district judges match Boyd's scores 99.2% of the time (within 0.02) and the circuit judges match the JCS scores 93.2% of the time, so the two published sources count senators differently.

Most differences under 0.02 are not errors. Voteview re-estimates the score of every member who is still serving whenever it adds a Congress, so judges whose senators are still in office (Fetterman, Rick Scott, Hickenlooper, and others) drift a little from scores published with an older file. The same is true of recent justices in the Martin-Quinn scores. The larger differences that remain are judges whom the published file places in a state that neither the center's records nor Wikipedia show (such as Richard Cudahy in Illinois and Stephen Trott in Idaho), a few D.C. Circuit judges and the Federal Circuit judges who came from the Court of Customs and Patent Appeals, which the published file scores differently, and some possible slips in the published files. The spreadsheet's check sheets list every comparison, and the next section explains every one that differs by more than 0.05.

Where they differ

These are every judge and justice whose computed score differs from the published one by more than 0.05, with the default settings. (The 689 other circuit judges, 2,529 district judges, and 780 justice-terms are within 0.05 of the published scores.)

Circuit judges and Epstein et al.

District judges and Boyd

75 of the 86 district judges who differ by more than 0.05 differ only because of how senators are counted. By default, the score counts every senator who sat in the Congress of the nomination; Boyd counts the senators who held the seats on the day, as --senators date does, which gives every one of these judges Boyd's score:

The other 11 differ for reasons that seem to lie in Boyd's file:

Justices and Epstein et al.

Using the published scores

--use-published (off by default) gives a judge or a justice's term the published score wherever it differs from the computed one by more than 0.05 (or --published-threshold): Epstein et al.'s for circuit judges and justices, and Boyd's for district judges. The Scores and Justices sheets then say where each score came from (jcs_source) and keep the computed score beside it (computed_jcs); the check sheets still compare the computed scores. With the default settings, it replaces the scores of 95 appointments since 1953 (80 district judges, 14 circuit judges, and Justice Jackson's appointment, from her first term) and of two justice-terms; with --senators date, it replaces 46 (13 district judges, 32 circuit judges, and Justice Jackson's).

Use it to reproduce the published scores, as when a study must line up with earlier work that used them. It is off by default because:

• The two sources count senators differently (Boyd by the day, Epstein et al. by the Congress), so taking both mixes their rules: with either setting of --senators, one of them is overruled.
• Some of the published scores that it would take look like slips, such as John Nalbandian's, Morris Arnold's, James Connell's, and the six New York and Kentucky judges'.
• Only judges in the published files can be replaced, so judges appointed in the same circumstances can end up with scores made by different rules.
• The published scores were made with older Voteview files, so they lag behind the current scores of senators who are still serving.

Getting started

Requirements

• Python 3.11 or later
• An internet connection, the first time, to download the source files (about 25 megabytes)

Installation

To install judicial_common_space, use pip:

pip install judicial-common-space

Usage

From the command line:

judicial-common-space --output judicial_common_space.xlsx

Or from Python:

import judicial_common_space

judicial_common_space.run('judicial_common_space.xlsx', start_year = 1953)

The spreadsheet has these sheets:

Contributing

Contributors are always welcome. Feel free to grab an issue to work on or make a suggested improvement. If you wish to contribute, please read the Contribution Guide and Code of Conduct.

Similar Projects

• courtpy adds the published JCS scores (and the other measures here) to court cases, and shares this package's downloads.
• The JCS scores of Lee Epstein, Andrew D. Martin, Jeffrey A. Segal, and Chad Westerland, for the judges of the courts of appeals and the justices.
• Christina L. Boyd's Federal District Court Judge Ideology Data, which scores district judges by the same rule.

Acknowledgments

The scores rest on the work and data of Epstein, Martin, Segal, and Westerland; Micheal W. Giles, Virginia A. Hettinger, and Todd Peppers; Keith T. Poole, Howard Rosenthal, and Voteview; Andrew D. Martin and Kevin M. Quinn; the Federal Judicial Center; the contributors to congress-legislators and to Wikipedia (whose text is available under the Creative Commons Attribution-ShareAlike License); and Christina L. Boyd. Please cite them when you use the scores.

This project was generated from @WithPrecedent's template.

Citation

If you use judicial_common_space in your research, definitely cite these works:

@misc{boyd_district_2015,
  author = {Boyd, Christina L.},
  title  = {Federal District Court Judge Ideology Data},
  year   = {2015},
  url    = {http://cLboyd.net}
}

@article{epstein_jcs_2007,
  author  = {Epstein, Lee and Martin, Andrew D. and Segal, Jeffrey A. and Westerland, Chad},
  title   = {The Judicial Common Space},
  journal = {Journal of Law, Economics, and Organization},
  volume  = {23},
  number  = {2},
  pages   = {303--325},
  year    = {2007}
}

@article{giles_picking_2001,
  author  = {Giles, Micheal W. and Hettinger, Virginia A. and Peppers, Todd},
  title   = {Picking Federal Judges: A Note on Policy and Partisan Selection Agendas},
  journal = {Political Research Quarterly},
  volume  = {54},
  number  = {3},
  pages   = {623--641},
  year    = {2001}
}

And, although my contributions to the JCS project are relatively minor, feel free to cite the repository as well:

@software{yung_judicial_common_space,
  author  = {Yung, Corey Rayburn},
  title   = {judicial_common_space: Judicial Common Space scores for every Article III appointment},
  version = {0.1.0},
  year    = {2026},
  url     = {https://github.com/WithPrecedent/judicial_common_space},
  license = {Apache-2.0}
}

License

Use of this repository is authorized under the Apache Software License 2.0.