Expert: District of Columbia Court of Appeals - per curiam, Judges Easterly and Shanker with Senior Judge Glickman concurring, Douglas v. Deutsche Bank Nat'l Trust Co., No. 24-CV-1099, Published order striking appellee's brief, filed 3 September 2026 Four of the authorities in appellee's brief in Douglas v. Deutsche Bank National Trust Co. (D.C. Court of Appeals, No. 24-CV-1099) do not exist. The panel did not need an outside tip to notice. While reviewing the brief before the appeal was submitted, Judges Easterly and Shanker and Senior Judge Glickman could not locate or confirm multiple citations, and on 22 June issued an order asking Deutsche Bank to show cause "why the court should not strike its brief for citing nonexistent cases that are possibly the product of artificial intelligence (AI) hallucinations." The attorney who prepared the brief, Loishirl W. Hall of McCabe, Weisberg & Conway, confirmed the next day that four cited authorities did not exist - Abadie v. District of Columbia, Cason v. Nat'l Consumer Co-op Bank, Osborne v. District of Columbia and Woods v. United States. She called them "not legitimate legal authority" and said they "should not have appeared in a brief filed with this Court." Her explanation is the part worth quoting precisely: she had "used Google's generative artificial intelligence search tool to assist in locating case authority," and she "did not verify the existence or accuracy of those citations before filing the brief." The firm told the court it was "unaware" of the hallucinations and that AI use in drafting is against policy, then shifted much of the blame to Hall, who had told the court she had never filed an appellate brief before this one and no longer works at the firm. The court struck the entire brief. It rejected the firm's suggestion that the filing could be accepted with the bad citations simply redacted - "that would constitute effectively no sanction at all" - and referred the matter to the Office of Disciplinary Counsel. Its warning reaches past this one filing: citing even a single fake case can be sanctionable, because "no brief, pleading, motion, or any other paper filed in any court should contain any citations - whether provided by generative AI or any other source - that" an attorney has not personally "read and verified." It also dismissed the idea that the rest of the brief being sound cures the harm: "Put bluntly-absolutely not; period; end of story; all stop." Judge Glickman's concurrence is the part practitioners should actually read. Fabricated citations, he wrote, are "only the tip of a perilous iceberg," and he cited Malkeet Lnu v. Blanche (9th Cir. 2026) for the distinction that matters: fabrications are cases or quotations that do not exist at all, while inaccuracies are real authorities cited for something they do not say. Fabrications are the notorious failure mode, but inaccuracies "may prove more dangerous to our profession in the long run" because they are not susceptible to a facial check and can only be caught by reading the cited source. He noted that legal-specific generative AI tools from Westlaw and Lexis hallucinated 17% and 33% of answers, respectively, to a representative set of queries run in 2024, with the most common error modes including misunderstanding holdings, presenting a rejected party's argument as the court's holding, and failing to respect the hierarchy of authorities - "the sort of errors that we might expect a first-semester law student to make, but certainly not licensed attorneys appearing before this court." Why the tool failed here is structural rather than incidental. Case law is a closed, checkable corpus: a citation either resolves to a real decision or it does not, and in Westlaw or LexisNexis that check takes seconds. A generative search tool asked to find authority for a proposition returns text shaped like authority whether or not authority exists, in the ordinary form of case names and citations, and that is precisely what survives a visual scan and a busy review. The court's rule is not a generic "verify your AI output" caution - it is that the verification duty attaches to the signature on the brief, and the AI tool does not carry it. Source: https://www.dccourts.gov/sites/default/files/2026-09/Douglas%20v.%20Deutsche%20Bank%20Nat%27l%20Trt%20Co.%2024-CV-1099%20ORDER.pdf