Don’t use AI for your citations in a brief to the Court! Clinco v. Comm’r filed February 9, 2026 by the U.S. Tax Court at T.C. Memo 2026-16 is a reflection of a growing problem in judicial filings, by both by represented and unrepresented parties.  This is a pretty basic case about an IRS exam where the IRS used bank deposit analysis to propose adjustments to the taxpayer’s gross income.  The IRS also pulled and compared 1099-K information. Ultimately a Notice of Deficiency was issued and the taxpayer hired counsel to represent him in Tax Court.  Unfortunately, counsel made some poor choices in his representations to the Court.  Taxpayer’s support for his positions were based on mostly fabricated cases! It turns out that 3 of the 4 cases his lawyer cited to the Court did not exist and as the Court states, “appear to be hallucinations generated by a large language model AI.” Based on this, “[t]he persuasiveness of Clinco’s argument collapses like an overmixed souffle.” In this case, the Court looked past all of these issues to get to the substance of the matter which still didn’t favor the taxpayer. This may not always be the case. The Court provided warning however: “Submitting a brief with fictitious caselaw is a recipe for sanctions and a clear violation of Rule 11(b) of the Federal Rules of Civil Procedure. We reiterate Chief Justice Roberts’s advice to lawyers who write briefs with citations of nonexistent cases: ‘[a]lways a bad idea.’” Rule 11(b) requires a lawyer or unrepresented party to certify to the Court that their submission is warranted by existing law or nonfrivolous argument for extending or modifying existing law.  Rule 11 also includes sanctions, which can take nonmonetary directives, monetary sanctions, or orders to pay other parties reasonable attorney fees and costs.  In sum, a bad idea all around.