Let me tell you about Sullivan & Cromwell.
One of the most storied law firms in the United States — over 900 lawyers, blue-chip clients, a reputation built across two centuries — walked into a federal bankruptcy court in April 2026 and issued an apology. The filing they had submitted contained inaccurate legal citations. Errors produced by artificial intelligence.
It made international headlines. But here is the thing: it was not an American story. It was a global one.
A French researcher named Damien Charlotin, who maintains the most comprehensive public database of AI hallucination cases in legal proceedings, has now catalogued over 1,353 such incidents across courts worldwide — with the pace accelerating sharply. The United States accounts for the largest share, but cases have been documented in the United Kingdom, Canada, Australia, and beyond. Reported incidents have grown from roughly two per week in early 2025 to two or three per day by the end of the year.
We have crossed a threshold. AI is no longer a curiosity being tested in the corner of a law firm's IT department. It is embedded in the workflow of practitioners on every continent. And it is, regularly and consequentially, getting things wrong.
So here is the question that the legal profession is now being forced to answer in real time — everywhere: When the AI lawyer gets it wrong, who pays?
The Problem Is the Same in Every Jurisdiction
To understand the liability question, you first need to understand what AI hallucination actually looks like in a legal context. It is not always clumsy or obvious. It often looks authoritative — exactly like the kind of citation a careful associate would produce after a long night in a law library.
Courts across multiple jurisdictions have identified the same recurring categories. First: citations to cases that simply do not exist — invented docket numbers, invented parties, invented holdings. Second: fabricated citations to real cases, where the case exists but the quoted passage does not. Third, and most insidious: citations to real quotes from real cases that directly contradict the legal proposition being argued.
That third category should frighten every practitioner. Because it does not just waste a judge's time — it can actively mislead a court on the state of the law.
An Australian federal court put the nomenclature issue bluntly in JML Rose Pty Ltd v Jorgensen in August 2025, refusing to call these outputs "hallucinations" at all: "More properly, such erroneously generated references are simply fabricated, fictional, false, fake and as such could be misleading." That framing matters. The word "hallucination" sounds like an accident. "Fabricated" sounds like what it actually is when it reaches a court unchecked.
Cases Are Coming from Every Direction
The geographical spread of documented incidents tells you everything about the scale of the problem.
In the United Kingdom, the Divisional Court dealt with exactly this issue in Ayinde v London Borough of Haringey and Al-Haroun v Qatar National Bank in 2025. A solicitor had relied on case citations provided by their client — citations that turned out to be fabricated or inaccurate material sourced from generative AI. The key finding: despite the client being the original source of the error, the solicitor was held accountable for failing to verify the information. The duty to the court transferred to the lawyer regardless of where the error originated. The Bar Council of England and Wales had already warned in 2024 that blind reliance on AI risked incompetence or gross negligence. The Law Society followed in May 2025 with a checklist that effectively codified AI literacy as a baseline professional competence. Courts, the Judicial Office made clear in April 2025, will forgive litigants in person for AI errors. They will not forgive regulated lawyers.
In Canada, the Ontario Superior Court confronted Ko v Li in 2025, a matrimonial case in which the applicant's counsel submitted a factum relying on several "Canadian court cases" that could not be located. When the judge investigated, one hyperlink directed the reader to a completely unrelated case; another produced a 404 error. The lawyer faced contempt of court sanctions. The case demonstrated that the hallucination problem is not confined to the large commercial litigation and corporate law contexts where it first attracted attention — it is present in family courts, in routine disputes, wherever AI tools are accessible.
In Australia, the Federal Court in Murray on behalf of the Wamba Wemba Native Title Claim Group v State of Victoria flagged AI-generated errors in 2025, and Australian legal bodies have issued increasingly detailed guidance in response. A joint statement from the Law Society of New South Wales, the Legal Practice Board of Western Australia, and the Victorian Legal Services Board was unambiguous: lawyers cannot safely enter confidential client information into public AI tools, and commercial AI tools require careful contractual review before any client data is processed through them.
In the United States, the sanctions wave has been the most extensively documented. US courts imposed over $145,000 in AI hallucination sanctions in the first quarter of 2026 alone. Oregon handed down a record $110,000 penalty. Nebraska issued what appears to be the first licence suspension directly tied to AI misconduct. The Sixth Circuit Court of Appeals dismissed a case entirely in March 2026, citing "pervasive misconduct" that rendered the appeal "almost entirely frivolous." And then there is Gordon Rees Scully Mansukhani — a top-100 firm by revenue — which apologised, updated its AI policies, implemented citation-checking procedures, and then, according to a subsequently filed brief, apparently submitted fabricated citations again.
The common thread across all of these jurisdictions is identical: the courts have been unambiguous that responsibility for accuracy never transfers to the machine.
So Who Is Actually Liable?
The practising lawyer is, for now, the answer — everywhere. The Colorado Supreme Court stated it plainly in a case involving a suspended attorney: "The use of artificial intelligence does not relieve an attorney of the obligation to verify the accuracy of all representations made to the court." This principle is not distinctively American. It reflects the basic structure of professional duty that exists in every common law jurisdiction and in the civil law traditions of continental Europe. The technology changes; the duty of candour does not.
The concept of "willful blindness" is doing a lot of work in judicial reasoning. By 2026, after years of widely publicised sanctions, warnings from bar associations globally, and professional guidance in virtually every jurisdiction, the argument that a practitioner was unaware of the hallucination risk simply does not hold. Courts are treating it as equivalent to knowing the risk and choosing to look away.
What about the vendors?
This is where it gets genuinely complicated — and where different jurisdictions are beginning to diverge in potentially significant ways.
Legal AI products are sold on the premise that they are specifically designed for legal research, with safeguards that generic tools lack. Yet the sanctions wave includes incidents involving purpose-built commercial legal tools, not just general consumer AI. The terms of service for nearly every legal AI product currently disclaim accuracy warranties and push responsibility back onto the user. Those disclaimers have not yet been seriously stress-tested in a products liability context. But the first major malpractice claim attributable to a commercial legal AI tool will test them — and some will not survive.
In the European Union, the regulatory framework is hardening in ways that may accelerate this reckoning. The EU AI Act is approaching its most significant enforcement milestone: most core obligations take effect on August 2, 2026. The Act is explicit that AI may support the decision-making of judges but must not replace it — and it codifies in law the human oversight principle that courts have been developing through hallucination case decisions. Critically, the EU AI Act has extraterritorial reach: it applies to any provider or deployer of AI systems whose outputs are used within the EU, regardless of where the company is based. Legal technology vendors operating internationally cannot treat European compliance as optional. Penalties for the most serious violations exceed GDPR maximums — up to €35 million or 7% of worldwide annual turnover, whichever is higher.
What about the firm?
Supervising partners carry exposure that may be underestimated. Courts in the United States have been clear that supervisory responsibility does not evaporate because the AI error originated with a junior associate or an external tool. If the signature is on the filing, the signatory is accountable. Over 35 US state bar associations have issued guidance extending supervisory obligations explicitly to AI use by junior staff. UK and Australian bodies have taken equivalent positions. A firm that allows AI tools to operate in client work without meaningful oversight, without verification protocols, and without training on hallucination risks is not merely negligent in the colloquial sense. It may be negligent in the legal sense — with all the malpractice exposure that implies.
There Is a Quieter Problem Nobody Wants to Name
There is a liability question embedded in all of this that the profession has been reluctant to surface directly: what happens when the AI error is not a fabricated citation, but a subtler analytical failure?
Fake case citations get caught, eventually, because judges check. They are embarrassing and sanctionable, but they are also recoverable — the filing gets struck, the attorney gets fined, the case continues.
What about an AI-generated contract analysis that misses a governing-law clause? What about a due diligence report that fails to flag a material liability because the model was not current on a recent regulatory development? What about a cross-border compliance survey that passes clean because the AI did not capture a jurisdiction-specific rule enacted three months ago — a rule that now exposes a client to criminal liability?
These failures are harder to detect, harder to attribute, and potentially far more costly. A Baker McKenzie partner observed in January 2026 that faulty citations in court filings are identified relatively easily, but oversights in complex contracts, due diligence reports, and regulatory surveys will prove much harder to catch. That is not a reassuring framing. That is a warning about the next phase of this problem.
There is also a dimension that Australian legal bodies have been particularly forthright about, and that deserves wider attention: legal professional privilege. A US federal court held in February 2026, in United States v Heppner, that material processed through AI may lose the confidentiality necessary to sustain a privilege claim — and that advice generated by AI, rather than by a lawyer, may never attract privilege in the first place. Uploading client documents to a public AI platform is, in the view of multiple courts and regulators, inconsistent with maintaining confidentiality. The implications for cross-border transactions and international arbitration, where privilege questions are already complex, are significant and barely discussed.
One Framework, Many Gaps
The emerging global picture is one of convergence on principle — human oversight is mandatory, verification is non-delegable, the machine cannot be blamed — and divergence on mechanism. The EU is moving toward binding statutory obligations with substantial penalties. The UK is relying on existing professional regulators and guidance rather than new legislation. The United States is locked in a federal-versus-state conflict over AI regulation that has left practitioners uncertain about which rules apply. Australia is advancing through professional body guidance rather than primary legislation, at least for now.
The result is a patchwork that works reasonably well for a domestic practitioner in a single jurisdiction and poorly for any lawyer doing international work. A firm advising a client on a cross-border acquisition using AI tools across multiple jurisdictions faces a matrix of professional obligations, privilege risks, confidentiality rules, and regulatory requirements that no current AI tool is designed to navigate.
That gap — between how legal AI tools are marketed and what international legal practice actually requires — is where the next wave of liability exposure is quietly accumulating.
A Final Thought
I am not arguing that lawyers should not use AI. They should. The efficiency gains are real, the access-to-justice implications are significant, and the practitioners who refuse to adapt will ultimately harm their clients.
But the current moment — in which adoption is racing ahead of both ethics rules and product accountability, across every jurisdiction simultaneously — is genuinely risky. Courts from London to Toronto to Sydney to New York are losing patience in parallel. The jurisprudence is developing faster than the professional frameworks designed to contain it.
When the first major malpractice verdict attributable directly to AI-generated error lands — and it will — the question "who's liable?" will have an answer. The profession should not wait for a court to provide it.