Key takeaways
In June 2023, a lawyer in Mata v. Avianca filed a brief with six court cases that ChatGPT had invented. He paid a $5,000 sanction.
Three years later, a database kept by a legal researcher lists more than 1,400 cases in which lawyers cited authority that didn’t exist. Over 900 of them are in US courts.
Read properly, the list is a map. It shows where AI does real work in law and where it stops. And nearly every sanctioned lawyer crossed the line the same way.
Where AI earns its place
Roughly 79 percent of lawyers now use AI. The strongest uses are narrow: contract review, due diligence, comparing documents, pulling clauses and obligations out of thousands of pages.
In each one, the source is in front of the model. The output can be checked against it. A person reviews it before anything binds.
Ask the model to supply the law from memory and file the answer unchecked? Then it’s a liability with a licence to practise.
The sanctions mark the line
After Mata the cases kept coming.
In Lacey v. State Farm, a special master imposed about $31,000 after roughly nine of 27 citations in a brief were wrong and at least two cases didn’t exist. He wrote that the output had nearly misled him into putting the bogus citations in an order.
The Sixth Circuit sanctioned two lawyers in Whiting v. City of Athens for, among other things, citing more than 24 invented authorities.
The Alabama Supreme Court sanctioned one lawyer who was told he’d cited a made-up precedent. He then cited nonexistent cases again in the very next sentence.
Even Sullivan & Cromwell had to apologise for a motion with about 28 erroneous citations.
Each is the same failure. The authority was generated instead of looked up, and filed unchecked.
A Stanford analysis found some legal AI tools invent answers to about one query in three. They do it more often on harder arguments, exactly when a lawyer most wants a supporting case.
Five seconds against a reputation
A rushed lawyer asks a model for support. It gives a real-sounding case name with a real-sounding quote. It goes into the brief unchecked.
Then the other side or the judge can’t find it. A five-second shortcut becomes a sanctions order with the lawyer’s name, the firm’s name and the word “fabricated” on it. It’s permanent and searchable, and more and more often it comes with a referral to the bar.
That imbalance is why the profession agreed so fast. Rule 11, ABA Formal Opinion 512 and a growing set of judges’ standing orders all point to one duty. Check every citation before filing, whether the draft came from a junior associate or a model.
So the model belongs in the firm as a first-pass reader of material you can check. Use it to read the contract, compare the clauses, summarise the deposition and find the obligation buried on page 340. Then open the reporter before you file anything it says about the law.
The 1,400 are lawyers who let a research assistant sign the brief. The people down the hall doing contract review, checking as they go, aren’t in the database.
Frequently asked questions
Is it safe for lawyers to use AI?
For narrow, checkable tasks like contract review, due diligence and document comparison, AI is widely used and works well. Around 79 percent of lawyers use it in some way. The danger is using it to produce legal authority that's then filed without checking. That's what has led to court sanctions.
Why do AI tools invent fake cases?
Language models generate likely-sounding text instead of looking up checked facts. So they can produce real-looking case names, quotes and citations that don't exist. A Stanford analysis found some legal AI tools make things up on roughly one in three queries, and more often on difficult arguments.
Have lawyers actually been punished for this?
Yes. Courts have imposed fines, public reprimands and bar referrals. That runs from the $5,000 sanction in Mata v. Avianca in 2023 to roughly $31,000 in Lacey v. State Farm, plus appeal-court sanctions in the Sixth Circuit. More than 1,400 such cases are now tracked worldwide.
What is the rule for using AI in legal work safely?
Treat AI as a first-pass reviewer of documents you can check, never as a source of authority you can't. The duty to check every citation before filing can't be handed off, under Rule 11 and ABA Formal Opinion 512. That holds whether a person or a model wrote the draft.
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