In legal writing, cf. is an introductory citation signal, short for the Latin confer (“compare”), that tells the reader the cited authority does not directly state the writer’s proposition but supports a different, analogous one worth comparing. Among the standard signals used in American legal citation, cf. sits between direct support and outright contradiction, and using it precisely matters more than most writers expect.
What “Cf.” Actually Signals
When you introduce a citation with cf., you are telling the reader two things at once: the cited source does not say what you just said, and the source is close enough by analogy to lend indirect support. If see means “this authority backs me up,” cf. means “this authority isn’t on point, but compare the two situations and you’ll see why my argument holds.” The source and the proposition share a logical thread even though they address different specific claims.
The practical consequence is that a reader encountering cf. knows not to expect the cited authority to mirror the writer’s language. Instead, the reader is being invited to look at the cited source and draw the analogy. That is why an explanatory parenthetical is treated as essential after a cf. citation. Without one, the reader is left guessing at the comparison, and few readers will pull up the source to work it out.
When “Cf.” Is the Right Signal
The most common scenario is a case that involves similar legal reasoning or analogous facts but does not decide your exact issue. If you are arguing that a particular contractual clause is unconscionable and the strongest case you have found deals with unconscionability in a different type of contract, that case does not directly support your specific claim, but its reasoning is analogous enough to bolster your argument. Cf. captures that relationship accurately.
It also fits when you cite authority from a different jurisdiction. If you are writing on a point of Fourth Circuit law and the closest case comes from the Ninth Circuit applying a similar but distinct standard, cf. tells the reader the citation is offered for comparison, not as binding or directly on-point authority.
The signal is not limited to case law. If you are arguing for a particular reading of one federal statute and a different statute uses similar language that courts have already construed, cf. is appropriate. The test is always the same: does the source support a different but analogous proposition?
What a “Cf.” Citation Looks Like
A complete cf. citation typically reads: Cf. Burd v. Walters, 868 F.2d 665, 668 (4th Cir. 1989) (noting that advice of counsel may be a defense in a criminal contempt proceeding because it negates the element of willfulness). The parenthetical does the real work. It explains what the case says and, by implication, how it relates to the writer’s proposition. Strip the parenthetical away and the reader has no way to understand why the comparison matters.
Why the Parenthetical Is Not Optional
No citation rule formally requires a parenthetical after cf., but omitting one is a mistake. Both the Bluebook and the ALWD Guide to Legal Citation strongly recommend explanatory parentheticals with cf. citations. The whole purpose of the signal is to invite a comparison, and the parenthetical is where you tell the reader what to compare. A cf. citation without a parenthetical fails at the signal’s core job.
Formatting Rules
When cf. appears as an introductory signal before a citation, italicize it (or underline it, depending on your document’s convention). If cf. functions instead as the verb of a textual sentence that incorporates the citation, it stays in regular type. The italicized introductory use is far more common.
Capitalize the “C” only when cf. begins a new citation sentence. Mid-sentence, or within a citation clause, keep it lowercase. The period after “cf” is always present because it is an abbreviation, and it stays even when the citation continues in the middle of a sentence.
The Bluebook and the ALWD Guide agree on the core meaning and use of cf. One small difference between the two systems involves comma placement in certain compound signals: the Bluebook inserts commas in some compound signals but not all, while the ALWD Guide consistently omits them. For cf. standing alone, the formatting is the same under either system.
Where “Cf.” Sits Among the Other Signals
Legal citation signals follow a prescribed order, and knowing where cf. sits helps clarify what it communicates. The standard sequence runs: [no signal], e.g., accord, see, see also, cf., compare … with …, contra, but see, but cf., see generally. Supportive signals come first, then comparison signals, then contradiction signals, and finally background signals.
Cf. falls at the tail end of the supportive group, just before comparison and contradiction signals begin. That placement reflects its character: it is the weakest form of support, sitting one step above signals that flag authority working against your position. When multiple signals appear together, all supportive signals (including cf.) join by semicolons within one citation sentence, while contradiction signals like but see go in a separate citation sentence.
The distinction that trips writers up most often is see versus cf. If the cited authority supports your actual proposition, even indirectly, use see. If it supports a different proposition that happens to be analogous, use cf. The dividing line is whether the source addresses your issue or a related but distinct one. On the contradiction side, but cf. is the mirror image: authority that supports a proposition analogous to the contrary of your argument.
Common Mistakes to Avoid
The most frequent error is using cf. when the source actually supports the proposition directly. If a case says what you are arguing, you do not need the reader to draw an analogy. Drop cf. and use no signal or see. Using cf. in that situation undersells the authority and makes the support look weaker than it is.
The second common mistake is omitting the explanatory parenthetical. Cf. without a parenthetical forces the reader to locate the cited source, read it, and guess at the comparison the writer had in mind. The parenthetical is where the analogy gets explained, and without it the signal does not do its work.
A subtler problem is reaching for cf. when the analogy is too thin to be useful. Every citation should earn its place, and cf. citations especially, because they ask the reader to do extra work. If the connection requires a full paragraph of explanation, the source probably is not worth citing. The best cf. citations involve comparisons that click quickly once the parenthetical points the reader in the right direction.
Finally, watch punctuation in string citations. When cf. appears alongside other supportive signals like see or see also, they belong in the same citation sentence, separated by semicolons. Contradictory authority introduced by but see goes in a separate citation sentence. Mixing supportive and contradictory signals within a single citation sentence is a formatting error that is easy to make when juggling multiple authorities.