Dec v. Mullin: What a Seventh Circuit Opinion on Inadmissibility Waivers Can Teach Us About Hallucinated Citations
A key best practice in litigation is to check every case cited in your adversary’s brief before drafting your opposition or response. The Seventh Circuit’s recent decision in Dec v. Mullin demonstrates why, criticizing counsel for failing to identify their adversary’s use of hallucinated cases.
The core issue in Dec v. Mullin is the statutory framework governing judicial review of immigration actions. But right from the introduction, the Court made it clear that it was going to dedicate a significant portion of its opinions to the petitioner’s use of “non-existent citations” and a “false quotation,” both “tell-tale signs of AI hallucinations.”
Importantly, the Court observed that the use of AI in litigation is evolving and “will only become more common and sophisticated.” But problems arise when “trained lawyers fail[] to check the accuracy of legal citations and quotations in their filing.” While the Court’s admonition was focused on the petitioner’s lawyer, who was responsible for the false citations, the Court also criticized opposing counsel for “fail[ing] to catch these errors and bring them to our attention,” noting that it gave them pause, “albeit to a lesser degree.”
The message is clear: while AI use in litigation may be inevitable, outsourcing judgment is not. Courts expect lawyers—not tools—to stand behind the accuracy of every citation. That responsibility doesn’t stop with our own briefs. As this case shows, it extends to what our adversaries put before the court as well.
Verifying citations isn’t just good practice—it’s part of our duty to reduce confusion, conserve judicial resources, and maintain credibility with the court.
Read the Seventh Circuit’s recent decision here