Short-Form Legal Citations: Id., Supra, and Hereinafter

Short-form legal citations let you reference a source you have already cited in full without repeating the whole entry. Under the Bluebook, the correct short form depends on what you are citing (case, statute, regulation, secondary source, or online material) and how recently the full citation appeared. The rules below cover each type, the proximity requirements, and the places writers most often slip up.

When You Can Shorten a Citation

Every source must appear once in full before any short form is allowed. After that first appearance, a short form works if three conditions are met: the reader can tell which source you mean, the full citation sits within the same general discussion, and the reader will have little trouble locating that original entry.¹

Practitioner documents (briefs, motions, memoranda) apply a flexible judgment-based standard. Law review footnotes are stricter: a short form is only appropriate when the full citation appears in the same footnote or within the five preceding footnotes. Beyond that window, re-cite in full.

Using “Id.” for the Immediately Preceding Source

“Id.” (from the Latin idem, “the same”) replaces the entire preceding citation when your current reference points to the exact same authority.² If the page or section is also the same, “Id.” stands alone. For a different page in the same source, add “at” and the new page number:

Same page: Id.
Different page: Id. at 15.

The period at the end of “Id.” is italicized along with the word itself. Editors check that reflexively.

“Id.” only works when the immediately preceding citation contains a single authority. If the last citation strung two or more sources together with a semicolon, “Id.” becomes ambiguous and you must use the source-specific short form instead.² In law review footnotes, “Id.” works within the same footnote or when citing the sole authority from the immediately preceding one.

Short Forms for Cases

When a case has been cited in full earlier but is not the immediately preceding authority, Rule 10.9 provides a condensed format built around a single party name, the reporter information, and a pinpoint page.³

Full citation: Smith v. Jones, 500 U.S. 200, 210 (1991).
Short form: Smith, 500 U.S. at 210.

Choosing the Right Party Name

Use the first party’s name unless that would confuse the reader. In United States v. Williams, the correct short form is Williams, because “United States” appears as a party in countless cases and tells the reader nothing. The same reasoning applies when the first party is a state or city. If the opening party is “State of California” or “City of New York,” use the other party’s name.

Building the Short Form

After the shortened case name, add the volume number, reporter abbreviation, and the pinpoint page preceded by “at.” That “at” is essential. It signals that you are pointing to a specific location inside the opinion rather than to the case’s starting page. In practitioner documents, the case name is underlined or italicized. In law review footnotes, it is always italicized.³

Short Forms for Statutes

Statutes run on different logic than cases or secondary sources. After a full statutory citation, later references typically drop the act name and date, leaving just the code abbreviation and section number, or sometimes just the section number if the context makes the statute obvious.⁴

Code and section: 42 U.S.C. § 1983.
Section alone (when unambiguous): § 1983.
Distinctive act name: the Civil Rights Act.

Statutory short forms do not use “at” before the section number. The section symbol itself is the locator. You also do not use “supra” for statutes. The code-and-section format is the correct short form. Treating a statute like a secondary source and writing “supra note 5” is a common error in student papers and occasionally in filings.⁴

Short Forms for Administrative Regulations

Federal regulations in the Code of Federal Regulations follow a pattern similar to statutes under Rule 14.4. After a full citation, you can drop the regulatory title and date and keep the volume, “C.F.R.,” and the section number:

Full citation: FTC Credit Practices Rule, 16 C.F.R. § 444 (2024).
Short form: 16 C.F.R. § 444.
Minimal form (when unambiguous): § 444.

Federal Register citations behave differently because they point to a specific page in the daily publication rather than a codified section. The short form keeps the title of the proposed rule and the volume, then adds “at” before the pinpoint page, as in “Importation of Fruits and Vegetables, 60 Fed. Reg. at 50,381.” The “at” returns here because you are pointing to a page within a volume, much like a case citation, rather than to a self-contained section number.

Using “Supra” for Secondary Sources

Books, law review articles, reports, treatises, and similar secondary materials use “supra” (Latin for “above”) to send the reader back to the footnote where the full citation first appeared. Rule 4.2 governs this form and limits it to specific categories of authority.⁵

The basic format is the author’s last name, the italicized word “supra,” a reference to the original footnote number, and a pinpoint:

Johnson, supra note 12, at 45.

“Supra” may be used for legislative hearings, court filings, books, pamphlets, reports, unpublished materials, periodicals, treaties, and regulations of intergovernmental organizations. It should not be used for cases, statutes, constitutions, restatements, model codes, or domestic regulations. Those have their own dedicated short forms. Newer legal writers stumble here most often, reaching for “supra” when citing a case they mentioned ten pages back, when the correct move is the Rule 10.9 case short form.⁵

Using “Hereinafter” for Cumbersome Titles

When a source has a long or unwieldy title, Rule 4.2(b) lets you assign a shorter label on first appearance and use that label going forward. It is appropriate when a bare “supra” would be impractical or confusing, for instance when two sources by the same author appear in the same footnote.⁵

The hereinafter label goes in square brackets at the end of the first full citation, before any explanatory parenthetical:

Full citation: International Commission on the Future of Environmental Compliance Mechanisms, Final Report on Global Standards 14 (2024) [hereinafter Final Report].
Later short form: Final Report, supra note 8, at 22.

The shortened label stays in the same typeface as the original citation. “Hereinafter” applies to the same categories of authority as “supra” and cannot normally be used for cases, statutes, or constitutions unless the name is extraordinarily long.

Short Forms for Internet Sources

Online-only materials (web pages, blog posts, documents available only on the internet) use the “supra” form from Rule 4 for their short-form citations. You do not need to repeat the URL. The full URL appears once in the initial citation, and every later reference uses the author’s name or the page title followed by “supra” and the original footnote number.

Source with an author: Gantenbein, supra note 1.
Source without an author: Weird and Dumb International Laws, supra note 3.

Keep whatever formatting and typeface you used in the full citation. If the title was italicized originally, keep it italicized in the short form. The same proximity requirements apply: the reader must still be able to find the original footnote without difficulty.

Practitioner Documents vs. Law Review Footnotes

The Bluebook maintains two parallel systems. The Bluepages govern practitioner documents like briefs, motions, and memoranda. The main body (sometimes called the Whitepages) governs law review and other academic publications. Short-form rules differ in two important ways.

The first is proximity. Practitioner documents allow a short form as long as the full citation sits within the same general discussion and the reader can locate it without much effort.¹ Law review footnotes tighten the standard: a short form only works if the full citation appears in the same footnote or within the five preceding footnotes. Outside that range, re-cite in full.

The second is typeface. In practitioner documents, case names in short-form citations may be underlined or italicized. In law review footnotes they are always italicized. The practical difference is small, but journals enforce it rigorously.

Common Mistakes to Avoid

Using “Id.” after a multi-source citation. If the preceding string contained two authorities separated by a semicolon, “Id.” is off limits. Use the source-specific short form.
Using “supra” for cases or statutes. Cases take the party-name short form from Rule 10.9. Statutes take the code-and-section format from Rule 12.10. “Supra” is reserved for secondary sources and the other categories listed in Rule 4.2.
Dropping “at” from case pinpoints. The short form Smith, 500 U.S. 210 is wrong. It needs “at”: Smith, 500 U.S. at 210.
Adding “at” to statutory citations. The reverse mistake. “§ at 1983” makes no sense; the section number is already the locator.
Choosing the wrong party name. If the first-listed party is the United States, a state, or a city, use the other party’s name. Williams tells the reader something; United States does not.
Exceeding the five-footnote window in law review writing. Practitioner documents give you more room. Law review footnotes do not.

The underlying principle is consistent across the rules: a reader who hits any short-form citation should be able to identify the source and find the original full entry without hunting for it. When you are unsure whether a short form works, re-cite in full.

1
The Bluebook Online. B10.2 Short Form Citation
2
The Bluebook Online. Bluebook Rule 4.1 – Id
3
The Bluebook. Rule 10.9 – Short Forms for Cases
4
The Bluebook Online. Bluebook Rule 12.10 – Short Forms for Statutes
5
The Bluebook Online. Bluebook Rule 4.2 – Supra and Hereinafter