The Phantom Precedents of the Seventh Circuit: When Legal Copy-Paste Goes Wrong

The collision between modern technology and tight filing deadlines has birthed a uniquely 2020s genre of professional embarrassment. In the spring of 2026, the United States Court of Appeals for the Seventh Circuit delivered an opinion in Dec v. Mullin, No. 25-2417 (7th Cir. Mar. 30, 2026), that serves as a cautionary tale on the state of contemporary legal drafting.

The case achieved notoriety across the federal bar because the petitioner's opening brief included two non-existent case citations and an entirely fabricated quotation.

The Algorithmic Fiction

The error occurred in the most mundane, perfunctory section of the entire appellate brief: the standard of review. Chief Judge Brennan’s opinion noted that the brief cited "two cases that do not exist" and recounted an "imaginary quotation." The court immediately identified these errors as bearing the "tell-tale signs of AI hallucinations," a phenomenon where artificial intelligence large language models (LLMs) generate fictional outputs that mimic genuine information.

When confronted with these phantom precedents during oral argument, the petitioner’s counsel did not mount a defense of her research methodology. Instead, she deployed a uniquely modern defense: absolute technological ineptitude. She claimed to be "way too technologically challenged to even attempt to use AI."

In a post-argument letter, she explained that she "presumably copied and pasted that portion from another brief several months ago," though she was unable to locate the original source document. She expressed deep regret and took full responsibility, explaining that her firm’s caseload had "dramatically expand[ed]" due to increased immigration enforcement in Chicago.

Asleep at the Wheel: The Opposing Counsel’s Miss

While the petitioner's counsel bore the primary responsibility for injecting fictitious law into the record, the Dec v. Mullin opinion exposes a secondary, equally concerning breakdown: the failure of the adversarial system itself.

The Seventh Circuit panel explicitly noted that the attorneys representing the government "also failed to catch these errors and bring them to our attention." The court admitted that this failure gave them "pause, albeit to a lesser degree."

The adversarial system relies on opposing parties to rigorously test each other's legal theories. When the petitioner submitted a brief containing non-existent law, the primary safeguard should have been the government's response. The fact that government litigators missed an imaginary quotation and two fake cases suggests a pervasive "boilerplate fatigue." Because both sides failed to verify the standard procedural section, the burden of fact-checking shifted entirely to the appellate judges and their clerks, generating "unnecessary work on a case within a case."

The Court’s Admonishment

Faced with confirmed fabricated citations and a defense of technological incompetence, the Seventh Circuit—comprising Chief Judge Brennan, and Circuit Judges Easterbrook and Taibleson—had to determine the appropriate response.

The court displayed remarkable leniency. It decided to publicly "admonish" the attorney but chose to "impose no other sanction." The court found her claim of not knowingly using AI to be "plausible" because the errors were "few" and strategically useless, merely supporting an undisputed standard of review. The court was also persuaded by her "acceptance of responsibility and sincere apology."

However, the court established a clear expectation for the bar moving forward. The opinion warned that checking the accuracy of legal citations and quotations is "easier now than ever," explicitly noting that entire briefs can be submitted to automated tools on Westlaw or LexisNexis.

Dec v. Mullin serves as a stark reminder. Ignorance of technology is no longer a valid excuse for the failure to verify, precisely because technology has made verification instantaneous. Whether a lawyer actively prompts an AI or simply copies and pastes blindly from an old document, they own the words they submit to the court.