US Law Firm Apologizes After AI Hallucinations Cause Dozens of Errors in Court Filing

Major US law firm Sullivan & Cromwell has issued a formal apology to Martin Glenn, Chief Judge of the US Bankruptcy Court for the Southern District of New York, after submitting a legal filing containing around 40 incorrect citations linked to artificial intelligence hallucinations.

In a letter sent on Friday, Andrew Dietderich accepted responsibility for the errors, stating that the firm regretted the incident and acknowledged its obligation to ensure accuracy under Local Bankruptcy Rule 9011-1(d). The flawed emergency motion had been filed nine days earlier, highlighting how reliance on AI tools without proper oversight can create serious risks in legal proceedings.

Growing Global Concern Over AI Hallucinations in Legal Work

The case reflects a broader trend of AI-related mistakes in court filings. A database maintained by Damien Charlotin has recorded 1,334 incidents of AI hallucinations in legal submissions worldwide, including more than 900 cases in the United States. Most errors involved fabricated legal citations, although inaccurate arguments have also appeared in some filings.

Dietderich explained that the firm already had policies requiring citation checks and verification procedures, but these safeguards were not properly followed in this instance. He noted that the review process failed to identify both AI-generated inaccuracies and additional manual errors.

Internal Investigation Underway After Rival Firm Flags Mistakes

The issue was ultimately detected by rival law firm Boies Schiller Flexner LLP, prompting immediate action. Dietderich confirmed he personally contacted the firm to thank them for identifying the mistakes and to apologize directly.

As part of its response, Sullivan & Cromwell has launched an internal investigation and implemented remedial measures, including reviewing staff training and evaluating whether stronger oversight procedures are necessary. The firm, ranked 30th on the AmLaw Global 200, has also been involved in high-profile cases, including representing FTX during its bankruptcy proceedings.

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