How to check whether a case is still good law

A case is still good law when no later decision or statute has overruled, reversed, vacated or superseded the holding you want to rely on. To check, run the case through a citator, read every negative citing decision it surfaces, and confirm the specific proposition you are citing survived.

That is the two-sentence version. The rest of this guide covers what a citator actually tells you, how to read the flags, the difference between subsequent history and treatment, and how to do the whole check without a Westlaw or Lexis subscription.

Why the question matters

Citing a case that has been overruled is one of the fastest ways to lose credibility with a court. Opposing counsel will find it, the clerk will find it, and Rule 11 of the Federal Rules of Civil Procedure requires that the legal contentions in a filing be "warranted by existing law or by a nonfrivolous argument" for changing it. A brief that treats an overruled case as controlling does not meet that standard.

The problem is that bad law rarely looks bad. The opinion still sits in the reporter. The reasoning still reads well. Chevron U.S.A., Inc. v. Natural Resources Defense Council was cited tens of thousands of times over forty years, and every one of those citations became a potential trap the day the Supreme Court decided Loper Bright Enterprises v. Raimondo in June 2024. Nothing on the face of Chevron changed. You had to check.

What a citator is

A citator is an index that runs backwards. Instead of telling you what a case cites, it tells you every later authority that cites the case, and, for the good ones, what those later authorities said about it.

There are two commercial citators that most US lawyers know:

• KeyCite on Westlaw (Thomson Reuters)
• Shepard's on LexisNexis, which is where the verb "to Shepardize" comes from

Both are editorially reviewed: a person classified the treatment. Free alternatives are automated. CourtListener lists citing opinions. Google Scholar has a "How cited" tab. The Frix Law Library runs an automated citator across its 10.8 million opinions and shows red and yellow flags, the sentence each citing case uses, and short parentheticals.

For a longer explanation of how citators work and where they fail, see What a citator is.

What the flags mean

Every citator has its own icons, but the logic is the same across all of them.

Two things trip people up.

First, a red flag does not always mean the whole case is dead. Opinions decide several issues. A case overruled on a jurisdictional point may remain the leading authority on a substantive one. The commercial citators try to tell you which headnote was affected. An automated citator usually cannot, so you have to read the overruling opinion and compare.

Second, a yellow flag is not a reason to abandon a case. Courts distinguish cases constantly. If the distinguishing decision turned on facts your matter does not share, the case is still good for you. If it turned on the exact point you need, it is a problem you have to confront in the brief rather than hope nobody notices.

Subsequent history versus treatment

These are two different questions and a careful check answers both.

Subsequent history is what happened to this case in this litigation. Was the decision appealed? Affirmed, reversed, vacated, remanded? Did the Supreme Court deny certiorari? A trial court opinion that was reversed on appeal is not good law regardless of how many other courts cited it in between. Subsequent history is what you cite in the parenthetical after the citation, for example "aff'd, 123 F.4th 456 (2d Cir. 2025)".

Treatment is what other cases, in other litigation, said about this one. This is where "overruled", "distinguished", "followed" and "criticised" live. Treatment does not go in your citation, but it determines whether the case is still worth citing.

A case can have clean subsequent history and terrible treatment. A district court opinion that nobody appealed can be overruled in effect when the circuit later decides the issue the other way. A case can also have negative subsequent history that does not matter: reversed on other grounds, with the point you need left intact.

A step-by-step check

Here is the process most litigators follow, whether they do it on Westlaw, Lexis or a free tool.

1. Pull the case itself and read the part you are citing. Confirm the case actually says what you think it says and note which issue it is. Everything downstream is about that issue, not the case as a whole.
2. Check subsequent history. Look for an appellate decision in the same litigation. On a commercial platform this is the "History" tab. On a free tool, search the party names and look for later opinions from a higher court with the same caption.
3. Run the citator and sort for negative treatment. Start with anything marked red. Then yellow. Ignore neutral citations for now.
4. Read every negative citing decision. Not the summary. The decision. Find the paragraph that discusses your case and ask: does it reach the point I need? Is it from a court that binds mine? Is it a majority opinion or a dissent? Automated citators sometimes flag a case because a dissent criticised it, which is not negative treatment at all.
5. Check for a superseding statute. Citators catch this inconsistently. If the case interprets a statute or rule, confirm the statute has not been amended since the decision. The statutes scope of the Law Library marks repealed and superseded sections, and our guide to confirming a statute is current walks through the check.
6. Look at the most recent citing cases in your jurisdiction. Even without a flag, if your circuit or state supreme court has not cited the case in a decade and has decided similar questions differently, that is a signal. Recent positive citations from a binding court are the best evidence a case is still good.
7. Record what you did. Note the date, the tool, and the negative treatment you reviewed and why it does not apply. If the case is challenged later, you will want that note.

Common mistakes

• Trusting the flag without reading the case. Editors and algorithms both make mistakes. The flag is a pointer, not a conclusion.
• Checking the case but not the cases it relies on. If your case's reasoning rests entirely on an earlier decision that has since been overruled, your case is weakened even if nobody has formally said so. Check the key authorities one level up.
• Stopping at the first jurisdiction. A case may be good law in the Ninth Circuit and rejected in the Fifth. Check treatment in the court you are actually in front of.
• Forgetting unpublished decisions. Many negative treatments come from unpublished or non-precedential opinions. They may not bind anyone, but a judge who wrote one is unlikely to have forgotten it.
• Citing a case that was later overruled on a different point without saying so. If the case has a red flag, and you are relying on a surviving holding, say so in the parenthetical: "overruled on other grounds by ...". Opposing counsel will see the flag either way.

How to do this in Frix

The Frix Law Library is free and does not require an account. To check a case:

1. Open cases and search by citation or party name.
2. On the opinion page, look for the flag at the top. Red means a citing case says it was overruled, reversed or abrogated. Yellow means it was distinguished, criticised, limited or questioned.
3. Open the citing references. Each one shows the exact sentence in which the later court cited the case, plus a short parenthetical, so you can tell from the list which references matter before you open them.
4. Click through to any citing case and read the surrounding discussion.

You can also ask Donna at /ask. Three questions are free without an account. Ask "Is [case name] still good law in the Second Circuit?" and she will search the library, run the citator, and answer with numbered citations you can click to open the source.

Two honest limits. The Frix citator is automated, not editorially reviewed like KeyCite or Shepard's, so it can miss an implicit overruling or mislabel a discussion, and it does not tell you which headnote was affected. And a small share of older opinions in the library are scans without text, which the citator cannot read. If a case matters to your brief, read the citing decisions yourself. That is true of every citator, but it is especially true of a free one.

For how Frix compares to the commercial platforms on this, see Frix vs Westlaw and Frix vs LexisNexis.