California Supreme Court on AI Misuse: Cervantes Footnote 7

By Alex (J.D. candidate, not a lawyer)

On September 24, 2026, the California Supreme Court decided Cervantes v. Bianco. In footnote 7, the court disapproved of "the improper use of artificial intelligence tools" in a brief filed in the case. It reminded counsel of two professional duties and referred the matter to the State Bar of California.

An "AI hallucination" in a court filing is text that an AI tool produces and presents as real when it is false. Common examples are a quotation a court never wrote or a case that does not exist.

This page explains what the footnote says, the rules it cites, and how it fits with other published California opinions. It is general information about the law. It is part of our California AI Law Tracker coverage.

The case in brief

The case was about ballots from Riverside County's November 4, 2025 special election. The county sheriff's department seized about 650,000 ballots under search warrants. Four county voters asked the Supreme Court to order the ballots returned to the Registrar of Voters.

The court held that the seizure was unlawful. It relied on Elections Code section 15551, subdivision (d). Before a September 2026 amendment, that subdivision said that "[i]n no event" shall voted ballots "be taken from the custody of the elections official." The court said the amended version is "at least as protective of ballots." The court ordered the ballots returned to the registrar.

Footnote 7 appears in the part of the opinion about standing, which is the question of who may bring the case.

Footnote 7, in the court's words

Here is the full footnote:

"In his preliminary briefing, Bianco challenged petitioners' standing based on misquoted passages from, and an incorrect recitation of our holding in, Common Cause v. Board of Supervisors (1989) 49 Cal.3d 432 (Common Cause). The law firm responsible for the error apologized and withdrew Bianco's standing argument. We disapprove of the improper use of artificial intelligence tools, which apparently contributed to the significant error that occurred here and remind counsel of attorneys' professional duties of competence and candor to the court. (See Rules Prof. Conduct, rules 1.1, 3.3.) We also refer the matter to the State Bar of California to determine whether discipline is warranted. (See canon 3D(2) of the California Code of Judicial Ethics.)"

(Read the official text, footnote 7.)

What the error was

According to the footnote, a brief:

  1. misquoted passages from a real California Supreme Court case, Common Cause v. Board of Supervisors (1989) 49 Cal.3d 432, and
  2. stated that case's holding incorrectly.

The footnote does not say the brief cited a case that does not exist. It says the law firm apologized and withdrew the argument. The court said AI tools "apparently contributed" to the error.

The two duties the court named

The footnote cites two California Rules of Professional Conduct. These rules apply to lawyers.

What the law says. Rule 1.1(a) says a lawyer "shall not intentionally, recklessly, with gross negligence, or repeatedly fail to perform legal services with competence." Comment 1 to the rule says this duty includes keeping up with "the benefits and risks associated with relevant technology." (Read the official text.)

Rule 3.3 covers candor toward the tribunal, meaning honesty with the court. Under rule 3.3(a)(1), a lawyer may not knowingly make a false statement of fact or law to a court, or fail to correct a false statement of material fact or law the lawyer made earlier. Under rule 3.3(a)(2), a lawyer may not "knowingly misquote to a tribunal the language of a book, statute, decision or other authority." (Read the official text.)

What it means in general. The court reminded counsel of these duties. The footnote itself makes no finding that any rule was broken. That question goes to the State Bar.

The referral to the State Bar

The court referred the matter to the State Bar "to determine whether discipline is warranted." It cited canon 3D(2) of the California Code of Judicial Ethics.

What the law says. Canon 3D(2) says: "Whenever a judge has personal knowledge, or concludes in a judicial decision, that a lawyer has committed misconduct or has violated any provision of the Rules of Professional Conduct, the judge shall take appropriate corrective action, which may include reporting the violation to the appropriate authority." (Read the official text, Canon 3D.)

What it means in general. A referral sends the question to the State Bar. The State Bar decides what happens next. As of the date at the top of this page, we have found no public report of any outcome. Separate statutes require courts to report certain sanctions to the State Bar. We explain those in when California courts report sanctions to the State Bar.

Other published California opinions on AI-generated errors

The California Courts of Appeal have also addressed AI-generated errors in published opinions. This list includes only published opinions we have read in full.

Noland v. Land of the Free, L.P. (2025)

Noland v. Land of the Free, L.P. (2025) 114 Cal.App.5th 426 was filed on September 12, 2025, by the Second District Court of Appeal, Division Three. The court found that briefs contained fabricated legal citations produced by AI. It noted that "no California court has addressed this issue" before. It then wrote:

"We therefore publish this opinion as a warning."

The court went on to say that no paper filed in any court should contain citations, "whether provided by generative AI or any other source," that the responsible attorney "has not personally read and verified."

The court imposed a monetary sanction on counsel. It directed counsel to serve the opinion on the client and directed the clerk to serve the opinion on the State Bar. (Read the official text.)

Del Biaggio v. Bansen (2026)

Del Biaggio v. Bansen (July 10, 2026, A174647) is a published opinion from the First District Court of Appeal, Division Four. The court found that an opening brief contained "fictional quotations" attributed to real cases. It ordered counsel to pay sanctions "payable to the clerk of this court." It ordered the clerk to forward the opinion to the State Bar under Business and Professions Code section 6086.7, subdivision (a)(3). The court declined to award sanctions to the other side. (Read the official text.)

California rules on AI in court and in practice

These are the main California rules and guidance on AI in courts and law practice. Each links to its entry in our tracker.

  • Rule of Court 10.430. Requires California courts that allow generative AI use to adopt a use policy that covers topics including confidentiality, bias, and accuracy. In effect since September 1, 2025.
  • Standard 10.80. Gives judicial officers guidelines for using generative AI in their judging work, including checking AI material for accuracy. In effect since September 1, 2025.
  • State Bar's 2026 generative AI guidance. Explains how existing ethics duties apply to lawyers' use of generative AI. Approved May 14, 2026. It replaces the 2023 guidance.
  • Proposed AI comments to the Rules of Professional Conduct. A proposal only. It includes a proposed comment to rule 3.3 on verifying cited authority. The second public comment period closed August 6, 2026. Any adoption requires California Supreme Court approval.
  • SB 574. A law about attorneys and generative AI, including verifying AI outputs such as citations. Signed by the Governor on September 30, 2026 (Stats. 2026, ch. 858). It takes effect January 1, 2027.

What to watch

  • SB 574. Its rules for attorneys and arbitrators take effect January 1, 2027. The tracker entry shows its current status.
  • The State Bar proposal. Watch for a State Bar Board of Trustees vote on the proposed AI comments, and any later Supreme Court action.
  • New published opinions. We will add California published opinions on AI errors to the list above as courts issue them.

Sources

SentryHall publishes general legal information for educational purposes. It is not legal advice, and reading it does not create an attorney-client relationship. The author is a law student, not a lawyer. Laws change and apply differently to different facts. For advice about your situation, talk with a lawyer licensed in California. You can look up a lawyer's license status at calbar.ca.gov.

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