Infra or Supra: Short Citation Forms With Id. and Hereinafter

In legal writing, the choice between infra and supra comes down to direction: use supra (“above”) to point the reader back to a source or discussion that already appeared earlier in your document, and use infra (“below”) to point forward to something that appears later. Both are governed by the Bluebook, which sets specific limits on which authorities can take a supra short form and how each cross-reference must be formatted.¹

Which Sources Can Take Supra

Rule 4.2 controls this, and it is where most writers slip. Supra works as a short-form citation for books, pamphlets, reports, periodicals, unpublished materials, nonprint resources, legislative hearings, court filings, treaties and international agreements, and regulations or decisions of intergovernmental organizations.²

Supra does not work for cases, statutes, constitutions, legislative materials other than hearings, restatements, model codes, or domestic regulations.² A case you have cited ten times still cannot get a supra reference. For primary authorities, you use the short-form citation prescribed by their own rule (Rule 10.9 for cases, for instance), or id. when the preceding footnote qualifies. The only narrow opening is when the authority’s name is so long that the Bluebook treats it as an extraordinary circumstance.

Formatting a Supra Citation

Supra takes two formats depending on whether you are pointing to a previously cited outside source or to a section of your own writing.

Back to a Previously Cited Source

Write the author’s last name, a comma, supra in italics, then the word “note” in regular type followed by the footnote number where the full citation first appeared. Add “at” and a pinpoint page if needed:

O’Neill, supra note 15, at 45.

For multi-author works, include enough names to identify the source unambiguously, as in “Baude & Sachs, supra note 1, at 1136.” The author name must match exactly how it appeared in the original full citation, and the footnote number must point to where that full citation lives in the final version of the document.

Back to a Section of Your Own Document

For internal cross-references, use a signal such as “see,” then supra, then the location:

See discussion supra Part III.A.
See supra notes 53–57 and accompanying text.

The Bluebook treats the wording of internal cross-references as flexible, so you can phrase these naturally as long as the reader can find what you are pointing to.¹

Formatting an Infra Cross-Reference

Infra uses the same structural patterns as supra but points forward. Typical forms:

See infra notes 24–29 and accompanying text.
See infra Part IV.

There is an important asymmetry. Because infra references a source that has not yet been cited in full, you cannot use the author-name-plus-footnote format with it. “Smith, infra note 30″ is not standard practice, because at the point the reader encounters the reference, the full citation does not yet exist in the reading sequence. Infra almost always appears as an internal cross-reference to a section, part, or range of later footnotes.¹ Supra, by contrast, works both as a short-form source citation under Rule 4.2 and as an internal cross-reference under Rule 3.5.

Choosing Between Id. and Supra

This is the daily decision. Id. (short for idem, “the same”) refers to the single authority cited in the immediately preceding footnote or in the same footnote. If the preceding footnote cites only one source, use id. You can add a pinpoint page after id. to send the reader to a different location in that same source.

If the immediately preceding footnote cites multiple authorities, id. is off the table because the reader cannot tell which source you mean. In that situation, use a short-form case citation (for cases, under Rule 10.9) or supra (for the secondary sources Rule 4.2 permits).² The hierarchy: id. wins when available, supra steps in when it is not.

When Hereinafter Helps

Some sources carry names too long to repeat comfortably in every supra reference. The Bluebook lets you assign a shortened label by appending [hereinafter Short Name] to the end of the first full citation, before any parenthetical explanation. A lengthy government report cited in full the first time with [hereinafter Climate Report] can then be referenced later as:

Climate Report, supra note 8.

“Hereinafter” also solves the problem of two works by the same author introduced in the same footnote. If one footnote cites both a book and an article by Professor Smith, a later “Smith, supra note 4″ is ambiguous. Assigning each work a distinct hereinafter label at the outset removes the ambiguity.

Mistakes to Watch For

A handful of errors come up repeatedly in law review notes and briefs:

Using supra for a case or statute. No matter how many times you have cited it, a case takes a short-form citation under Rule 10.9 and a statute takes its own abbreviated form.²
Stale footnote numbers after editing. Numbers shift constantly during revision, and “supra note 12″ that was accurate in the second draft may point somewhere else after you insert three new footnotes. Verify every number against the final document before filing.
Using id. after a multi-source footnote. If the prior footnote cites two or more authorities, id. is unavailable. This slips in easily when you add a “see also” source to an existing footnote during revisions without updating the following footnote’s short form.
Forgetting the italics. Both supra and infra are italicized whenever they appear in a citation. The word “note” that follows them is not.

1
The Bluebook Online. The Bluebook – Rule 3.5 Internal Cross-References
2
The Bluebook Online. 4.2 Supra and Hereinafter