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GOOD LAW
Legal Citation Checker That Tells You If a Case Is Still Good Law
Check whether a case is still good law before you cite it, with a treatment signal that flags followed, questioned, and overruled decisions.
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CASESEARCH · RESEARCH
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Reading opinions
Finding the authorities that answer your question...
Controlling statute
The controlling statute is surfaced alongside the case law so you read the code and the precedents together.
Plain-English answer
Research memo
- Question
- Short answer
- Authorities
Casesearch shows you the sources. Always read the full opinion and verify citations before you rely on them.
What is legal citation checker?
A legal citation checker tells you whether a case is still good law, meaning it has not been reversed, overruled, or seriously questioned by later courts. Casesearch shows a treatment signal on every authority, followed, questioned, or overruled, and links you to the later opinions that treated it, so you confirm a precedent is alive before relying on it in a brief.
Last updated August 2026
4 citators
KeyCite, Shepard's, Authority Check, and BCite are the editorial citators in general use
$5,000
the Rule 11 sanction in Mata v. Avianca, the case that made citation checking a professional-responsibility issue
17% and 33%
hallucination rates Stanford researchers measured for two leading legal AI research tools
Every result
a treatment signal sits on the authority card, so verification is not a separate product
What you get
Built for legal citation checker
Every result gives you a real citation, a plain-language holding, and a still-good-law signal you can verify.
Followed, questioned, or overruled
A color-coded treatment chip on every case tells you its status at a glance.
See the treating opinions
Trace which later decisions followed or undercut the case so you can read them yourself.
Built into every result
You do not run a separate Shepardize step, the signal is on the authority card.
Verify before you file
The checker is the answer to AI hallucination fears, you confirm the case exists and still stands.
How it works
Ask, search, verify
Plain English in, cited authorities out, and you always read the opinion before you rely on it.
Step 01
Pull up the case
Find it from a search or paste the citation you want to check.
Step 02
Read the treatment signal
See whether the case is followed, questioned, or overruled.
Step 03
Review the treating cases
Open the later opinions that shaped its current status.
Step 04
Cite with confidence
Confirm in the full opinions, then rely on living law only.
What does a legal citation checker do?
It answers whether a case is still good law, and it does that by reading forward rather than backward. Your case was decided on a date. Everything that matters to whether you can rely on it happened after that date: a higher court reversed it, a later panel overruled part of it, a legislature superseded the statute it construed, or forty later courts followed it without qualification. A citator collects those later decisions and tells you what they did.
That is a different job from verifying that a citation is formatted correctly, and the two get conflated constantly. A cite checker in the law-review sense confirms that the volume, reporter, page, court, and year are right and that the source says what the sentence claims. A citator confirms the case is still authority. You need both, and a wrong Bluebook comma is the far smaller problem. Our walkthrough on how to read a legal citation covers the formatting side.
The third thing people now want from a citation checker is confirmation that the case exists at all. That was not a real concern before 2023 and it is a live one now. If an AI tool handed you a citation, the first question is not whether the case is good law. It is whether the case is a case.
Reads forward from the decision date
Everything that changes a case's status happened after it was decided.
Not the same as Bluebook checking
Format correctness and precedential status are separate problems.
Now also an existence check
Confirming the case is real is a step that did not used to exist.
Run it as its own step
Do not assume the search that found the case also checked it.
Why do lawyers need to verify AI legal citations?
Because courts have made it a sanctionable failure, and the numbers are no longer anecdotal. The case everyone knows is Mata v. Avianca, Inc., 678 F. Supp. 3d 443 (S.D.N.Y. 2023), in which Judge P. Kevin Castel imposed a 5,000 dollar Rule 11 sanction on June 22, 2023 after counsel filed a brief containing six fabricated decisions produced by ChatGPT. The sanction was modest. The professional damage was not, and the opinion is now cited routinely as the baseline expectation that a lawyer verifies what a machine hands them.
It stopped being one embarrassing outlier. Damien Charlotin maintains a public AI Hallucination Cases database tracking court decisions worldwide in which AI-generated content produced fabricated citations or other fabricated material, and by June 2026 it had grown to roughly 1,600 decisions, more than a thousand of them in the United States. Whatever the exact count on any given day, the shape is clear: this is a recurring failure mode, not a one-time story.
The uncomfortable part is that the problem is not confined to general-purpose chatbots. Stanford researchers evaluating purpose-built legal AI research tools, in work published in the Journal of Empirical Legal Studies in 2025, measured hallucination on more than 200 legal research queries and reported rates around 17 percent for Lexis+ AI and around 33 percent for Westlaw's AI-Assisted Research. Those are tools sold specifically to lawyers, grounded in real legal databases. The conclusion is not that legal AI is unusable. It is that the verification step is not optional at any price point, which is why we put the treatment signal and the link to the opinion on every result rather than behind a separate product. Our longer discussion is in avoiding AI hallucinated citations and can you trust AI for legal research.
Mata v. Avianca set the baseline
A 5,000 dollar Rule 11 sanction for six fabricated cases, June 22, 2023.
Roughly 1,600 tracked decisions
Charlotin's database had passed that by June 2026, over a thousand in the US.
Legal-specific tools hallucinate too
Stanford measured about 17 percent and about 33 percent for two major products.
Verification is a workflow, not a feature
Open the opinion and read the pinpoint before it goes in a brief.
What is the difference between a citator and a citation checker?
In everyday use the terms have collapsed into each other, and it rarely causes trouble. Strictly, a citator is the reference work: Shepard's Citations began as printed volumes listing every later case that cited a given decision, and KeyCite, Authority Check, and BCite are the modern equivalents. A citation checker is the tool or the task of running your authorities through one before filing.
The distinction that does matter is editorial versus algorithmic. An editorial citator employs attorneys who read the citing decisions and assign a signal, which is why a red flag on Westlaw or Lexis carries weight and why those products cost what they do. An algorithmic citator infers status from citation patterns, which is fast, cheap, and less precise at the margins. A reference-only tool such as CourtListener's Authorities and Cited By lists gives you the raw citing relationships with no judgment attached, which is genuinely useful and genuinely not the same thing. We compare that tradeoff in the CourtListener comparison.
Whichever kind you use, the signal is a triage tool rather than an answer. A yellow flag might mean a later court distinguished the case on facts nothing like yours, which is irrelevant to you, or that a concurrence questioned the exact holding you are relying on, which is fatal. The flag tells you where to look. It does not do the looking. Our guide on what a citator is goes deeper on the signals themselves.
Citator is the reference work
Shepard's, KeyCite, Authority Check, BCite.
Citation checking is the task
Running your authorities through one before you file.
Editorial versus algorithmic
Attorney-assigned signals cost more and read more precisely.
The flag is triage
It tells you which later opinion to read, not whether you win.
How do I check if a case has been overruled?
Pull the case, read the treatment signal, then open the decisions that produced it. That last step is the one people skip, and it is where the actual answer lives. A signal is a summary of other courts' behavior; the behavior is in the opinions.
Work through four questions in order. Was the case reversed on appeal, which ends the inquiry. Was it overruled by a later decision of the same court or a higher one, and if so, was the whole case overruled or only one holding, because partial overruling is common and often leaves the part you care about intact. Was the statute or rule it construed amended or repealed after the decision, which is the failure mode a case-focused citator is worst at catching. And has it been distinguished or criticized in a way that reaches your facts rather than someone else's.
Two habits close most of the remaining gap. Check treatment again immediately before filing, not only when you first found the case, because months can pass between research and filing and a case can lose its footing in that time. And check the reporting or precedential status separately from the treatment status, because in several states an opinion can be perfectly good law and still be one you are not permitted to cite. Our step-by-step is in how to check if a case is still good law, and how to Shepardize a case walks through the traditional process.
Reversed ends the inquiry
An appellate reversal is not a partial signal.
Overruling is often partial
Check whether the specific holding you rely on survived.
Watch the underlying statute
A superseded statute is the miss citators catch least well.
Re-check before filing
Status can change between research and the filing date.
Side by side
The legal citators, and what each one actually gives you
A citator answers one question: has a later court done anything to this case that changes whether you can rely on it. The differences between them are less about coverage than about whether a human being made a judgment call. Editorial citators pay staff attorneys to read the citing decisions and assign a signal. Algorithmic and reference-only tools show you the citing cases and leave the judgment to you, which is cheaper and slower and sometimes exactly what you need.
| Citator | Where it lives | How the signal is produced | What it costs to reach |
|---|---|---|---|
| KeyCite | Westlaw | Editorial, with attorney-assigned flags plus depth-of-treatment bars | Requires a Westlaw plan at a tier that includes it |
| Shepard's | LexisNexis | Editorial, with the traditional Shepard's signals | Included on the self-serve Lexis+ tiers |
| Authority Check | Fastcase and vLex | Algorithmic, based on citing-reference patterns rather than editors | Often included free with state bar membership dues |
| BCite | Bloomberg Law | Editorial, with composite analysis of citing opinions | Requires a Bloomberg Law subscription, which is quote-only |
| Authorities and Cited By | CourtListener | Neither: it lists citing and cited decisions with no treatment judgment | Free, from the nonprofit Free Law Project |
| Casesearch citation check | Casesearch | A treatment signal on every authority card with links to the treating opinions | Included from 39 dollars a month at launch, no separate citator seat |
Casesearch is a research accelerator, not legal advice. Read the treating opinions yourself and confirm the current status before you file.
Frequently asked
Questions about legal citation checker
What is a legal citation checker?
A tool that tells you whether a case is still good law by collecting the later decisions that cited it and reporting what those courts did. It flags cases that were reversed, overruled, questioned, or followed. It is distinct from Bluebook cite checking, which confirms that a citation is formatted correctly and that the source supports the sentence.
How do I check if a case is still good law?
Pull the case, read its treatment signal, then open the later decisions behind that signal and read them. Confirm it was not reversed or overruled, check whether any overruling was partial, and check whether the statute it construed has since been amended. Re-run the check immediately before filing, not only when you first found the case.
What is the difference between a citator and a citation checker?
A citator is the reference work that lists later citing decisions and assigns a treatment signal, such as KeyCite, Shepard's, Authority Check, or BCite. Citation checking is the task of running your authorities through one before filing. In practice the terms are used interchangeably, and the difference that matters is editorial versus algorithmic signals.
Is there a free legal citation checker?
CourtListener, from the nonprofit Free Law Project, shows Authorities and Cited By lists for free, and many state bars include a Fastcase or vLex library with the Authority Check citator in annual dues. The free options give you citing relationships rather than attorney-assigned treatment flags, which is a real difference at the margins.
Do I need to verify citations from AI legal research tools?
Yes, every time. Courts have sanctioned lawyers for filing AI-fabricated citations, starting with Mata v. Avianca, Inc., 678 F. Supp. 3d 443 (S.D.N.Y. 2023). Stanford researchers also measured hallucination rates of roughly 17 percent and 33 percent for two purpose-built legal AI research products, so the risk is not limited to general chatbots.
What does a yellow flag on a case mean?
That some later court treated the case negatively without overruling it, by questioning, criticizing, distinguishing, or limiting it. It is a prompt to read the treating opinion, not a verdict. A yellow flag from a case distinguished on facts unlike yours may not affect you at all, while one questioning the exact holding you rely on can be fatal.
Does a citation checker catch superseded statutes?
Not reliably. Case citators track how later courts treated a decision, so a case interpreting a statute that was later amended or repealed can carry a clean signal while the underlying law has changed. Check the current text and the amendment history of any statute your authority construes as a separate step.
Keep reading
Legal citator comparison
KeyCite, Shepard's, BCite, and the AI citators side by side.
What is a citator
What the signals mean and where they come from.
How to check if a case is still good law
The step-by-step treatment check before you file.
How to Shepardize a case
The traditional process, and what it looks like now.
Avoiding AI hallucinated citations
Why fabricated cases happen and how to catch them.
Can you trust AI for legal research
What the accuracy research actually measured.
CourtListener comparison
Excellent free coverage, and no treatment flags.
Case law search
Plain-English search that returns cited holdings.
How to read a legal citation
Reporters, pinpoints, parentheticals, and subsequent history.
More of Casesearch
Case law search
Court opinions search
Statute search
Precedent finder
Case summaries
Research memo
Small law firms
Solo attorneys
Paralegals
Litigation teams
Casesearch is a legal research tool, not legal advice. Always read the full opinion and verify citations before relying on them.
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