Research Guides: An Introduction to The Bluebook: Short Citation Forms (Id., Supra, Hereinafter)

Overview

Rule 4 governs the general use of the short citation forms id., supra, and hereinafter. Many source types have additional rules that supplement or override Rule 4. Refer to the table at the beginning of Rule 4 to identify exceptions.

Id.

Rule 4.1 addresses the use of id. (short for idem, meaning "the same"). Use id. when citing the immediately preceding authority, either:

within the same footnote, or
in the footnote directly above, provided that footnote includes only one authority.

When citing to the same authority but a different page, use id. at [new page].

Scenario	Example(s)	Explanation
Citing the same authority as in the immediately preceding footnote, which contains only one authority	Johnson v. Phelan, 69 F.3d 144, 145 (7th Cir. 1995). Id. Franklin A. Gevurtz, Building a Wall Against Private Actions for Overseas Injuries: The Impact of RJR Nabisco v. European Community, 23 U.C. Dᴀᴠɪs J. Iɴᴛ'ʟ L. & Pᴏʟ'ʏ 1, 2 (2016). Id. at 15.	Id. refers to the same authority cited in the immediately preceding footnote. Because that footnote contains a single authority, id. is permitted. A different page number may be specified by adding a pinpoint citation after id. (e.g., Id. at 15).
Citing the same authority as in the immediately preceding footnote, which contains multiple authorities	Johnson v. Phelan, 69 F.3d 144, 145 (7th Cir. 1995); Timm v. Gunter, 917 F.2d 1093 (8th Cir. 1990). Johnson v. Phelan, 69 F.3d at 145. Hannah L. Buxbaum, The Scope and Limitations of the Presumption Against Extraterritoriality, 110 AJIL Uɴʙᴏᴜɴᴅ 62, 63 (2016); see also Gevurtz, supra note 17, at 3. Buxbaum, supra note 20, at 64.	When the preceding footnote cites more than one authority, id. is not permitted. Use supra if permitted by Rule 4.2. Otherwise, use the appropriate short form for the authority.
Citing the same authority more than once in a single footnote	Pamela Laufer-Ukeles, Collaborative Family-Making: From Acquisition to Interconnection, 64 Vɪʟʟ. L. Rᴇᴠ. 223, 223 (2019). Laufer-Ukeles observes that "domestic adoption involves a widely-accepted system of what is considered 'non-commercial adoption,' even including private adoption . . ." Id. at 238.	Id. may be used within a single footnote when referring to the same authority cited earlier in that footnote.

Supra

Rule 4.2(a) governs the use of supra.

Use supra to refer back to an authority that was previously cited in full in an earlier footnote, unless id. would be more appropriate. Supra is only permitted for certain categories of materials.

Use supra for:	Do not use supra for:
Legislative hearings Court filings Books Pamphlets Reports Unpublished materials Nonprint resources Periodicals Services Treaties and international agreements Regulations, directives, and decisions of intergovernmental organizations Internal cross-references	Cases (see Rule 10.9) Statutes (see Rule 12.10) Constitutions (see Rule 11) Legislative materials (except hearings) (see Rule 13.8) Restatements (see Rule 12.9.4) Model Codes (see Rule 12.9.4) Regulations (see Rule 14.5) Refer to the specific Bluebook rules above for the appropriate short citation forms for these authorities.

Scenario	Example(s)	Explanation
Citing an authority previously cited in full, but not in the immediately preceding footnote	1. William Baude & Stephen E. Sachs, The Law of Interpretation, 130 Hᴀʀᴠ. L. Rᴇᴠ. 1079, 1107-10 (2017). 10. Baude & Sachs, supra note 1, at 1136. 5. Rocky Mountain National Park Act § 1, 16 U.S.C. § 191. 7. U.S.C. § 191.	When an authority was previously cited in full, but not in the immediately preceding footnote, use supra if permitted for that type of source under Rule 4.2. Otherwise, use an appropriate short citation form for the authority.

Hereinafter

Rule 4.2(b) governs the use of hereinafter. This short form is used in the first full citation of an authority to assign a shortened name to a long or complex title. Insert the word hereinafter and the shortened form in brackets directly after the citation and before any explanatory parentheticals.

For example, hereinafter may be used to reduce confusion when:

the authority has a long or complex title, or
multiple sources in the same footnote need to be distinguished.

In later citations to the same authority, use the assigned short form followed by a comma and the relevant supra reference.

Note: Hereinafter follows the same use restrictions as supra. For a list of authority types where use is not permitted, see the chart above.

Scenario	Example(s)	Explanation
Assigning a shortened name to an authority with a long or complex title	1. Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I), June 8, 1977, art. 10 [hereinafter AP I]. 10. AP I, supra note 1.	When a source's title is lengthy, assigning a shortened name using hereinafter improves clarity and avoids repetition in subsequent citations. The short name is used in later footnotes, followed by a supra cross-reference.
Distinguishing between multiple authorities by the same author in a single footnote	3. Lisa Pruitt, Who's Afraid of White Class Migrants? On Denial, Discrediting, and Disdain and Toward a Richer Conception of Diversity, 31 COLUM. J. GENDER & L. 196, 197 (2015) [hereinafter White Class Migrants]; Lisa Pruitt, Welfare Queens and White Trash, 25 S. CAL. INTERDISC. L.J. 289, 290 (2016) [hereinafter Welfare Queens]. 4. Pruitt, White Class Migrants, supra note 3, at 198.	Hereinafter is useful when multiple authorities by the same author appear in one footnote. Without it, later citations may be unclear. For example, if footnote 4 read “Pruitt, supra note 3, at 198,” it would be ambiguous which of the two sources in footnote 3 is being cited.