Opposing Counsel Fake Citations: How to Catch Them and What to File

If opposing counsel cited a case that doesn't exist, verify it, document what you found, and raise it before the court relies on it. Courts have begun denying fees and finding arguments forfeited when the receiving side stays silent about opposing counsel fake citations. The right remedy depends on the forum and on whether your opponent has a lawyer.

Opposing counsel fake citations: why silence costs you

These four decisions turn on the lawyer who received the fake citations, not the one who filed them.

Noland v. Land of the Free, L.P. (Cal. Ct. App., 2d Dist., No. B331918, Sept. 12, 2025), 114 Cal.App.5th 426. The court sanctioned appellant's counsel $10,000 for a brief with fabricated quotations, then declined to award sanctions to the respondents: "While we have no doubt that such sanctions would be appropriate in some cases, in the present case respondents did not alert the court to the fabricated citations and appear to have become aware of the issue only when the court issued its order to show cause." It added that the respondents never submitted a declaration of their fees and costs.

In re Domestic Partnership of Torres Campos & Munoz (Cal. Ct. App., 4th Dist., Div. 1, No. D085584, Mar. 5, 2026). The fake cases came from the respondent and her counsel. The appellant's counsel drafted the proposed order, the family court signed it, and it repeated the fictional cases. The appellate court agreed the trial court erred by relying on them, but held that the appellant forfeited the claim "by drafting and submitting the very order he now challenges and failing to object or alert the court that the cited authorities were fake." It sanctioned the respondent's counsel $5,000.

Nuvola, LLC v. Wright (Minn. Dist. Ct., Hennepin County, Nov. 21, 2025). The court sanctioned the lawyer who filed fake citations, then turned to opposing counsel. It found it "troubling" that he had not identified the nonexistent cases, because "[t]he Court should not be left as the last line of defense against citations to fictional cases in briefs filed with the court." It did not find his conduct sanctionable, since he cited no fake case, but "the Court reminds counsel that it is the obligation of counsel on both sides to respond to each other's arguments, including completing a basic cite-check of the cases cited by the other side."

Landberg v City of New York (N.Y. App. Div., 2d Dep't, 2026 NY Slip Op 03935, June 23, 2026; uncorrected slip opinion, subject to revision). The court sanctioned appellant's counsel $8,000 and his firm $2,500. It noted that the City's and the owner's lawyers "submitted respondents' briefs" and that "neither of them alerted this Court about the fabricated citations." It declined to award costs because neither respondent asked for them or submitted billing statements.

In none of these cases was the non-flagging lawyer sanctioned. The cost was lost fees, a forfeited argument, a judicial rebuke, and an unrecovered cost award. The lessons: raise the problem when you find it, and if you want fees or costs, ask for them and document them. For the filer's side, see our roundup of AI hallucination sanctions cases.

How to spot fake case citations in a brief

Run every authority through four questions, in order, starting with the ones the brief leans on hardest. Note any failure.

The second and third rows catch what a bare existence check misses. In Noland, most of the quotations were attributed to published cases that do not contain them. In Landberg, the brief cited a real Court of Appeals case for a rule about construing exceptions to remedial statutes, and the court found that the opinion "does not use the words remedial or exception."

For method, see our guides to cite-checking a brief, verifying AI-generated citations, and checking whether a case is still good law.

A fake citation does not prove the other side used AI, and you do not need to allege it. Describe what you verified: the nonexistent authority.

Document before you raise it

• Save the filed version of the brief with its docket number and filing date.
• For each bad citation, record the exact text cited, where it appears, what you searched and where, and the date.
• Screenshot or export the empty search results. If the reporter cite resolves to a different case, save that case's first page.
• Keep a short table of cite, defect, and the proposition the cite was offered for. The proposition shows whether the court may have relied on it.

The same file becomes your letter, your brief section, or your sanctions exhibits.

Contact opposing counsel first, with limits

A letter or call before you file is usually the right first move. The Virginia State Bar's draft Legal Ethics Opinion 1902 says that before notifying the court a lawyer "may consider reaching out to opposing counsel directly about the identified AI hallucinations and offering opposing counsel the opportunity to take corrective action." Draft LEO 1902, published for comment May 27, 2026. It is a proposed draft, not a final opinion, so check its status before relying on it.

The same draft says a lawyer who identifies material misstatements of law or fact in an adversary's pleading "should bring these issues to the attention of the court," and that where the hallucinations are abundant or particularly material they should be revealed to the tribunal. So the call is a courtesy and a path to correction. If material errors stay uncorrected, the draft points you to the court.

Put it in writing: list the citations, say you could not locate them, and ask for a corrected filing by a stated date. Do not threaten a bar complaint to gain an edge. The draft notes that Virginia Rule 3.4(i) bars threatening disciplinary charges solely to obtain an advantage in a civil matter. Check whether your state has an equivalent.

Skip the call when the error is plainly deliberate, a hearing is imminent, or the filing is about to become the basis for an order. Raise it in your own papers instead and serve a copy.

Trial court: pick the right vehicle

Under Fed. R. Civ. P. 11(c)(2), a motion for sanctions "must be made separately from any other motion and must describe the specific conduct that allegedly violates Rule 11(b)." It must be served, but "must not be filed or be presented to the court if the challenged paper . . . is withdrawn or appropriately corrected within 21 days after service or within another time the court sets." On fees: "If warranted, the court may award to the prevailing party the reasonable expenses, including attorney's fees, incurred for the motion." The 1993 advisory committee note says that party can be "the movant or the target of the motion," so a weak motion can cost you fees. Rule 11(b)(2) is the certification that legal contentions are "warranted by existing law or by a nonfrivolous argument" for changing it. A nonexistent case is neither.

Rule 11(c)(3) lets the court act on its own: it "may order an attorney, law firm, or party to show cause why conduct specifically described in the order has not violated Rule 11(b)." The safe harbor does not protect a filer from that.

State rules vary. Nuvola was decided under Minnesota's Rule 11 and a Minnesota statute, not the federal rule. Our Rule 11 sanctions guide covers the federal standard and process.

Appellate court: Rule 11 does not reach it

Rule 11 covers papers presented to a federal district court. Three of the four cases above were appellate.

In a federal court of appeals, FRAP 38 says: "If a court of appeals determines that an appeal is frivolous, it may, after a separately filed motion or notice from the court and reasonable opportunity to respond, award just damages and single or double costs to the appellee." A brief resting on invented authority is a strong candidate for that argument, though the rule asks whether the appeal itself is frivolous, so tie the fake citations to that showing. Rule 38 awards run only to the appellee. If you are the appellant and the answering brief is the problem, raise it with the panel. Under FRAP 46(c), a court of appeals may discipline an attorney who practices before it, after reasonable notice and an opportunity to show cause.

In state appellate courts, look to the state's rules and the court's own sanction power. Noland and Landberg were both sanctions imposed by the court itself after an order to show cause. A short letter or motion to the panel, with your table of defects attached, puts you on the record. Do it before argument if you can.

Is there a duty to report opposing counsel to the bar?

Not automatically. The Virginia draft opinion states Rule 8.3(a) this way: a lawyer must report another lawyer to the appropriate professional authority if the lawyer "has reliable information that the other lawyer has committed a violation of the Rules of Professional Conduct that raises a substantial question about the other lawyer's honesty, trustworthiness, or fitness to practice law." It adds that "[w]hether to notify the court or disciplinary authority" of apparently AI-hallucinated errors "requires the attorney to use professional judgment, taking into account the seriousness of the errors and other relevant circumstances."

Two cautions. That text is Virginia's, and other states word and apply the rule differently; our state-by-state guide to bar AI guidance is a starting point. And client confidentiality can limit what you may disclose. The draft points to Virginia's Rule 1.6(c)(2).

Courts sometimes raise discipline themselves. Landberg noted that whether disciplinary action is warranted "may be a matter for the Attorney Grievance Committee."

When the opponent is pro se

Unrepresented parties file AI-drafted briefs too. Verify and document the same way, start with a letter, and expect the court to weigh pro se status. In Matter of Julien v Arthur (2026 NY Slip Op 03308, 2d Dep't May 27, 2026), the mother's brief pointed out the fictional citation, and the court sanctioned the pro se father $250 for citing a single nonexistent case, weighing his pro se status, that he cited only one, and that he acknowledged his reliance on AI once alerted. Rule 11 applies to unrepresented parties in federal court as well, but a safe-harbor letter to a pro se litigant should be plain and free of threats. Attach your triage table so they can check your work.

Frequently asked questions

Do I have to tell the court when opposing counsel cites a fake case?

No federal rule says so in terms, but the risk of staying quiet is real. Courts have denied fees to, and found claims forfeited by, the side that did not flag fabricated citations, and a Minnesota trial judge called a basic cite-check of the other side's cases an obligation of counsel on both sides. Check your jurisdiction's rules and any standing order.

Does the Rule 11 safe harbor apply to an appellate brief?

No. Rule 11 governs papers presented to a federal district court. In a federal court of appeals the main vehicle is Rule 38 of the Federal Rules of Appellate Procedure, which reaches frivolous appeals, awards damages and costs only to the appellee, and requires a separately filed motion or notice from the court and a reasonable opportunity to respond. State appellate courts have their own sanction rules and inherent powers.

Am I required to report opposing counsel to the state bar?

Not automatically. Rule 8.3(a) in its Virginia form requires a report only when a lawyer has reliable information of a violation that raises a substantial question about the other lawyer's honesty, trustworthiness, or fitness. A single fake cite may or may not meet that test, and state versions of the rule differ, so read yours.

What if the fake citations are in a pro se litigant's filing?

Verify and document the same way, but expect the court to weigh pro se status. In Matter of Julien v Arthur, a New York appellate court imposed a $250 sanction on a pro se father who cited one nonexistent case. Rule 11 and its safe harbor still apply to unrepresented parties in federal court. Start with a plain letter that lists the citations you could not find.

Run the brief through the Shield

For the first pass, paste or upload the opposing brief into the free Hallucination Shield. It needs no account, checks up to 50 citations per run, and flags the ones it cannot verify. The top results show at once; an email address unlocks the full report. That is your starting list. The quotation and proposition reads above still need you. Inside CaseRead, the citing-case screen shows later treatment of the authorities that do exist.

This article is for general information and is not legal advice. For guidance on a specific case, consult a licensed attorney in your jurisdiction.