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Bluebook Introduction: Major Changes in the 21st Edition

The new 21st edition of The Bluebook was published in 2020. Below are lists of select changes.

Differences between the 20th and 21st Editions

21st Edition
1.4 No longer requires a prescribed order of authorities within each signal, instead requires authorities to be organized in a logical manner.
10.6.2 New section addresses how to cite SCOTUS in chambers opinions.
12.3.2 Citing to the U.S. Code no longer requires a year.
15.1(b) More than two authors for a non-periodical resource--use all author names when particularly relevant. Use the first author and et al. for short form citations.
18.2.2(c) Date and time for updated online sources--use the date and time when the piece was updated, rather than when it was originally posted.
18.2.2(d) Use short URLs when possible but only if the URL makes it clear what the source is. (E.g.,, but not
18.6-18.7 Provides direction for how to create a pinpoint citation to video and audio recordings.
18.8 New rule gives guidance for citing photographs and illustrations.
20/T2 Removes foreign jurisdictions citation guidance from the back of the Bluebook, in T2. The Bluebook directs the user to T2 online on the Bluebook's website.
T13/T6 Removes the separation in previous editions between T6 (abbreviations in institutional author and case names) and T13 (abbreviations in periodical titles). See chart (to the right) for a list of the new abbreviations.

T6 New Abbreviations for Words in Case Names, Institutional Author Names, and Periodical Titles

Word Old Abbreviation New Abbreviation

Artificial Intelligence

Comparative Comp. Compar.

Employ[er, ment]

Emp'[r, t] (T6) Emp.
Employ[ee, ment] Emp. (T13) Emp.
Environment[al] Envt'l Env't
Laboratory NONE Lab'y
Nationality Nat'lity Nat'y
Profession[al] Prof'l (T6), Prof. (T13) Pro.
Psycholog[ical, ist, y] Psychol. Psych.
Refin[ing, ement] Ref. Refin.
Research Res. Rsch.
Reserv[ation, e] Res. Rsrv.
Sociolog[ical, y] Soc. Socio.
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