Free legal citation checker
Verify the case citations in a brief before it is filed. Each one is looked up in CourtListener, and the case name you wrote is compared with the name on record, so an invented case or a real citation under the wrong name shows up before a judge finds it.
Paste the text or open a PDF or Word file. The document stays in this browser: citations are found on your own device, and the only thing sent anywhere is the volume, reporter and page of each one. No sign-up, no charge.
Faster with a free CourtListener token
Without a token, lookups are spaced five seconds apart to stay inside CourtListener’s anonymous limit. With your own token they run about four times faster. Get one free from yourCourtListener profile. It is sent only to CourtListener.
Everything that left this browserNo requests yet
Each request is shown as sent, URL-decoded so it reads (hover for the raw form). None contains your document; each carries one citation’s volume, reporter and page. Apart from these, the page downloads its own code once, from this site and cdn.jsdelivr.net. Answers are kept in this browser so a second run is instant.
The two citation errors behind the AI sanctions.
An AI hallucination in a legal brief almost always takes one of two forms, and a typo can produce either. The checker marks both.
In Mata v. Avianca (S.D.N.Y. 2023) two lawyers and their firm were fined $5,000 for a filing that cited six decisions ChatGPT had invented. Courts have kept sanctioning the same mistake since; the sanctions tracker lists the orders. Both kinds of error below are in the sample brief above.
A case that does not exist
A plausible name on numbers that point at nothing. This is what a chatbot usually produces when it invents authority, and what a tired associate produces with a typo.
In re Vance Capital Partners, 612 F. Supp. 3d 1187 (2022)
No case at that citation in CourtListener.
A real citation under the wrong name
The numbers resolve, so a quick lookup passes, but they belong to a different case. It is the invented citation that survives a careless check.
Okafor v. Tessaly Corp., 450 U.S. 248 (1981)
450 U.S. 248 is Texas Department of Community Affairs v. Burdine.
How to check the case citations in a brief.
- 01
Paste the brief or open the file
A motion, brief, memo or AI research answer. PDF, Word (.docx) or plain text. Scanned PDFs need OCR first.
- 02
Read the review list
Every full case citation gets a verdict. Start with “Needs a look”: name mismatches, unresolved citations and anything not checked.
- 03
Pull every flagged case
Open the CourtListener link or look it up in your research service. Fix the citation, or take the authority out.
- 04
Read the ones that resolved
A resolved citation exists. Whether it holds what you cite it for, and whether it is still good law, is still your call.
The checker covers the mechanical part of a cite-check. The rest of the routine, including the proposition and treatment checks no tool does for you, is in how to cite-check a brief.
- It does not prove a case was invented. It finds the citations that need a human look.
- It does not check that a case says what it is cited for. Existence is not support.
- It does not Shepardize or KeyCite. It cannot tell you whether a case is still good law.
- It does not check Bluebook format, quotations or pin cites.
- US case citations only. Statutes, rules and UK neutral citations are not read.
- eyecite, the Free Law Project’s citation parser, finds every full case citation. It runs in this tab.
- Each distinct volume, reporter and page is searched on CourtListener, about one every five seconds without a token.
- The case name in your document is compared with the name on record. Below 60% similarity is a mismatch.
- Unlike most AI citation checkers, no language model is involved at any step, so it cannot hallucinate an answer of its own.
On a labelled set of 20 test briefs with planted defects (invented citations, real citations under invented names, transposed digits) and two prompt-injection documents, every one of 116 citations got the expected verdict. The briefs are synthetic and cite well-known Supreme Court cases, so real filings with obscure authority will produce more unresolved results.
The code is open source: the same Python as the command-line verifier, running in your browser.
Questions lawyers ask about it.
Is this legal citation checker free?
Yes. There is no account and no charge. The only limit is CourtListener’s: without a token, lookups are spaced about five seconds apart, so a brief with 40 distinct citations takes a little over three minutes. A free CourtListener token makes it about four times faster.
Can it catch AI-hallucinated case citations?
It flags the two forms a hallucinated citation from ChatGPT or another AI tool takes: a citation that does not resolve, and a real citation carrying another case’s name. It cannot prove a case is fake. CourtListener’s coverage is thinner for unpublished opinions, very recent decisions and state trial courts, so an unresolved citation is a reason to check by hand, not a finding.
Is this an AI hallucination checker?
For case citations, yes. It is a citation verification tool: it catches the citations an AI invents, whether a case that does not exist or a real citation under the wrong name. It does not check the rest of an AI answer, such as a misstated holding or an invented quotation.
Is my brief uploaded or stored anywhere?
No. The file is opened and the citations are found inside your browser. The only data that leaves is the volume, reporter and page of each citation, sent to CourtListener, and every one of those requests is listed under the results.
Is it a Bluebook citation checker?
No. It does not check Bluebook formatting. It reads citations in the usual reporter formats and checks that each one points at the case you named. Signals, abbreviations, spacing, pin cites and short forms are not checked.
Does it replace Shepard’s or KeyCite?
No. A citator tells you whether a case has been reversed, overruled or questioned. This checks that the case exists at that citation under that name. Run a citator on every authority you rely on.
Which citations and courts does it cover?
Full US case citations to the federal and state reporters CourtListener indexes: U.S., S. Ct., F., F. Supp., the regional reporters and state official reports. Westlaw (WL) and Lexis citations are listed as not checked, because no open database holds them. Short forms such as “id.” and “supra” are not checked on their own.
Why was a real case marked unresolved?
Usually a transposed volume or page, which looks exactly like an invented case. Sometimes the case is missing from CourtListener or cited to a reporter it does not index. Look it up by name, correct the citation and run the check again.
Can I check opposing counsel’s brief?
Yes. Anything you can open or paste. Public filings downloaded from PACER or CourtListener’s RECAP archive work as PDFs.
A checker finds the citation. The habit has to live in the firm.
One lawyer running a check is a habit. A firm needs the check inside the filing workflow, on its own systems, with a named person signing off. If that is the gap at your firm, talk to us.