Illinois Appeals Court Warns Lawyers Against AI Hallucinations in Briefs
Illinois Appeals Court fines lawyer for AI-generated misstatements in a July 2026 brief.
Why it matters: The ruling is a rare judicial critique of AI use in law, highlighting risks of unverified AI arguments for attorneys. Legal professionals must ensure accuracy when using AI tools in filings.
- An Illinois lawyer admitted using a premier ChatGPT subscription to draft a July 2, 2026, response brief with legal misstatements.
- The Illinois Appeals Court imposed a higher fine to deter use of unverified AI-generated legal arguments.
- Since 2023, over 280 court filings included AI-generated hallucinated citations, with a sevenfold rise in 2025.
- In January 2025, the Illinois Supreme Court allowed ethical AI use but holds attorneys fully accountable for their work product.
The Illinois Appeals Court recently imposed a higher fine on an attorney who acknowledged using a "premier corporate subscription of ChatGPT" to draft a response brief filed on July 2, 2026. That brief contained misstatements of law attributed to AI-generated hallucinations, which the court warned against in hopes of deterring similar reliance by other lawyers. The court's decision reflects growing judicial concerns about unverified AI use in litigation.
This case is set against a backdrop of increasing incidents where AI hallucinations—fabricated or inaccurate legal citations generated by AI tools like ChatGPT—have infiltrated court filings. Records show over 280 filings since 2023 carry such hallucinated citations, with a sevenfold increase in 2025.
The Illinois Supreme Court acknowledged the reality of AI use by implementing a formal policy in January 2025 allowing responsible and ethical AI tool use without mandatory disclosure, while emphasizing attorneys remain fully responsible for their legal submissions. This policy balances AI innovation with professional accountability.
Legal ethics authorities have also responded; notably, on July 29, 2024, the American Bar Association issued Formal Opinion 512 addressing generative AI in law practice, underlining attorneys' duty to verify AI-generated content.
The warnings and sanctions underway in Illinois align with similar messages from other courts, such as the Arizona Court of Appeals, where Judge Brian Furuya stated, "Submission of hallucinated case citations—intentional or unintentional—is unjustifiable," emphasizing lawyers cannot excuse inaccuracies based on lack of intent. This stance signifies a firm judicial intolerance for reckless indifference to truth in legal filings.
For legal professionals, this development highlights the critical need for diligence when leveraging AI tools. While AI can aid drafting, ultimate responsibility for accuracy rests with the attorney, and courts are prepared to penalize failures rigorously.
By the numbers:
- 280+ court filings with AI hallucinated citations since 2023 — indicating widespread AI-related errors in legal documents
- 7× increase in hallucinated AI citations filings in 2025 alone — showing rapid growth of the issue
- January 2025 — Illinois Supreme Court's AI policy allowing ethical AI use while holding lawyers accountable
Yes, but: The Illinois Supreme Court permits responsible AI usage without requiring disclosure, balancing innovation with accountability.
What's next: Close monitoring of AI-related filings and potential further sanctions are expected as courts refine their approach to AI in legal practice.