In legal citation, supra vs. infra is a question of direction: supra means “above” and sends the reader back to a source or discussion already cited earlier in the document, while infra means “below” and points forward to material that appears later. Both are navigational shorthand that save space and keep briefs readable, and both have narrow rules about when they can be used.
What Supra Does
Supra tells a reader that the full citation for a source already appeared somewhere above. Once you’ve cited a secondary source in full, every later reference can use supra instead of repeating the whole thing. Under Bluebook Rule 4.2, this covers books, pamphlets, law review articles, periodicals, legislative hearings, court filings, reports, unpublished materials, treaties, and nonprint resources.
The standard format in footnote-heavy writing is: Author’s Last Name, supra note [number], at [page]. If footnote 12 contained the full citation for a treatise by Professor Feldman, a later footnote might read: “Feldman, supra note 12, at 87.” The “note” reference tells the reader which footnote holds the full citation, and the “at” directs them to a specific page. Practitioner documents like briefs and memoranda use the same structure.
What Infra Does
Infra works in the opposite direction, flagging material that appears later in the document. Writers reach for it most often for internal cross-references rather than source citations. A summary-of-argument section might say “See discussion infra Part III” to tell the reader the full analysis is coming without crowding the overview with detail.
Bluebook Rule 3.5 governs these internal cross-references. Under that rule, portions of text, footnotes, and groups of authorities within the same document can be cited using either supra or infra, depending on whether the material has already appeared or is still ahead. The wording is flexible: you can combine the signal with “See” or work it into a textual phrase.
Infra shows up far less often than supra because most citation work points backward to sources already introduced. Where it earns its keep is in structuring long documents. Appellate briefs with multiple argument sections, law review articles broken into roman-numeral parts, and research memoranda that build from general principles to specific applications all benefit from forward-pointing references.
How Supra Differs From Id.
New legal writers confuse supra with id. more than almost any other citation pair. Id. refers exclusively to the immediately preceding cited authority. If footnote 15 cites a single source and footnote 16 cites the same source, footnote 16 uses id. If the preceding footnote contains multiple authorities, id. becomes ambiguous and cannot be used. In that situation, you fall back on supra for secondary sources or the appropriate short form for cases and statutes.
Think of it as a one-step-back reference. Id. works only when the reader can glance at the single footnote directly above and know exactly which source you mean. Supra can jump back any number of footnotes or pages, which is why it needs the author’s last name and footnote number as anchors. One more wrinkle: id. can be used for any type of authority, including cases and statutes, as long as the immediately-preceding rule is satisfied. Supra cannot cross into primary sources regardless of proximity.
Sources You Cannot Use Supra For
This is where most citation errors happen. Writers learn that supra saves space and start applying it everywhere, but the Bluebook draws a hard line. The following categories require their own short-form citations and cannot use supra:
- Cases, which use the short-form case name under Bluebook Rule 10.9.
- Statutes, which use the short-form citation under Rule 12.10.
- Constitutions, which use the short form under Rule 11.
- Legislative materials other than hearings, including committee reports and floor debates.
- Restatements and model codes, which follow their own short-citation conventions.
- Regulations, including Federal Register entries and Code of Federal Regulations citations.
The only exception is extraordinary circumstances, such as when the name of the authority is absurdly long. If you’re citing a court opinion for the third time, you use the case’s short-form name, not supra.
Formatting Details
Both supra and infra must be italicized. The same applies to id. The Bluebook and the ALWD Guide agree on this. In court documents, some jurisdictions accept underlining as an alternative to italics, following the general convention that typeface distinctions can be rendered either way in practitioner work.
For supra citations pointing to a specific page, the word “at” separates the reference from the pinpoint page number: “Feldman, supra note 12, at 87.” Italicization covers supra itself but not the comma after it or the “at.” Small detail, easy to miss, and inconsistent formatting across a brief stands out to anyone reviewing it closely.
For infra cross-references, the format typically names the specific part or section: “See infra Part III.B” or “discussed infra Section IV.” Capitalizing the structural labels (Part, Section, Chapter) helps the reader locate the reference quickly.
The Hereinafter Option
When a source has an unwieldy title, the Bluebook allows a “hereinafter” designation that creates a custom short name for later supra references. The label appears in brackets at the end of the first full citation: [hereinafter Short Name]. Every subsequent reference then uses the short name with supra. This is especially useful for government reports, institutional publications, and international agreements whose titles run to fifteen or twenty words.
One formatting detail that gets botched regularly: the word “hereinafter” itself is not italicized, but the short name that follows it is. The correct form is [hereinafter Short Name], not [hereinafter Short Name]. The brackets must be present, and the construction belongs at the end of the full citation, not floating in body text.
Hereinafter shares the same category restrictions as supra. It applies to books, periodicals, reports, hearings, and similar secondary sources, and should not be used for cases, statutes, constitutions, or regulations except in the same extraordinary circumstances that allow supra for those authorities.
Mistakes That Stand Out
A few supra and infra errors appear so often in student papers and junior associate drafts that they’ve become a kind of shorthand for inexperience.
The most common is using supra for a case. It’s an easy mistake because cases are cited constantly and supra feels like the natural shortcut. Every time it appears in that context, though, it signals that the writer hasn’t absorbed the basic category distinction. Use the case’s short-form name instead.
The second most common error is using supra when id. is correct. If you’re citing the same source as the immediately preceding footnote and that footnote contains only one source, id. is mandatory. Reach for supra only when id. doesn’t work because of intervening citations or multiple sources in the preceding footnote.
On the infra side, the classic mistake is promising a discussion that never materializes. If you write “See infra Part V” and the document only has four parts, you’ve created a dead reference. This happens more often than you’d expect during editing, when sections get reorganized or cut. Any time you restructure a document, check every infra reference to confirm it still points somewhere real.