Top US law firm admits AI errors after fake citations surface in court
Sullivan & Cromwell has apologised to a US federal judge after submitting a court filing containing inaccurate citations and other errors generated by artificial intelligence.
In a letter dated 18 April 2026 to Martin Glenn, chief judge of the US Bankruptcy Court in Manhattan, Andrew Dietderich, co-head of the firm’s global restructuring group, acknowledged that the filing included AI “hallucinations”. These refer to instances where artificial intelligence produces fabricated case citations, misquotes legal provisions, or generates non-existent authorities.
Dietderich apologised to the court and confirmed that the errors were identified by opposing counsel from Boies Schiller Flexner, who are also involved in the proceedings. He stated that he had contacted the firm directly to thank them for raising the issue and to apologise.
The filing was submitted in connection with bankruptcy proceedings involving Prince Global Holdings Limited, a Cambodian conglomerate. The case relates to the winding down of the company, whose founder, Chen Zhi, has been charged in the United States with offences including alleged investment fraud and involvement in forced labour operations. The company has previously denied wrongdoing.
The firm confirmed that its internal policies governing the use of AI tools had not been followed. These policies require lawyers to verify any AI-generated content before it is used in legal work. The letter also stated that a secondary review process failed to identify the inaccuracies before the document was filed.
A corrected version of the filing has since been submitted to the court. The firm did not specify which AI tool was used or identify the individuals responsible for the error. No comment was immediately available from representatives of the firm.
The incident comes amid increasing scrutiny of the use of artificial intelligence in legal practice. While lawyers are permitted to use AI tools, professional obligations require them to ensure the accuracy of all submissions made to the court.
US judges have previously imposed sanctions in multiple cases where legal professionals relied on AI-generated content without adequate verification. The risks associated with such tools have prompted law firms to introduce internal policies and training aimed at minimising errors.
Sullivan & Cromwell, based in New York and employing more than 900 lawyers, is widely regarded as one of the leading corporate law firms in the United States, with a strong focus on mergers and acquisitions, corporate governance, and restructuring matters.
The case highlights ongoing challenges surrounding the integration of artificial intelligence into legal workflows, particularly in high-stakes litigation where accuracy remains critical.