Sullivan & Cromwell Faces Backlash Over AI Hallucinations in Court Filings

Prominent Wall Street law firm Sullivan & Cromwell has issued a formal apology to a federal judge after submitting a court filing containing inaccurate legal citations generated by artificial intelligence, according to multiple news reports published on April 21, 2026.

The firm acknowledged that the document included so-called AI “hallucinations,” where the technology produced fabricated or incorrect legal references. These errors were identified by opposing counsel from Boies Schiller Flexner during proceedings in the U.S. Bankruptcy Court for the Southern District of New York.

Andrew Dietderich, co-head of Sullivan & Cromwell’s global restructuring group, addressed the court in a letter dated April 18, 2026, taking responsibility for the mistake. In the correspondence to Chief Judge Martin Glenn, Dietderich stated that he apologized on behalf of the entire firm and had also contacted Boies Schiller Flexner directly to express regret for the errors.

Sullivan & Cromwell confirmed that while it has established comprehensive policies governing the use of AI tools in legal work, those guidelines were not followed in this instance. The firm further noted that an internal secondary review process failed to detect the inaccurate citations before the filing was submitted.

A corrected version of the document was later filed with the court. The incident underscores growing judicial scrutiny of AI-generated content in legal proceedings, with U.S. Judges having sanctioned attorneys in numerous cases for relying on unverified artificial intelligence outputs.