Lahti v. Consensys Software Inc.
U.S. District Court, Southern District of Ohio · S.D. Ohio · Ohio bar guidance
Conduct
Pro se plaintiff cited fictitious cases in objections and reply briefs in employment-related action against Consensys.
Consequence
Sanctions declined; warning of severe sanctions including monetary sanctions for future false citations.
Lesson
Hopkins chambers warned in Lahti (Aug 2025) of monetary sanctions for future false citations; Lattimore (Jan 2026) repeated the posture.
Verified May 14, 2026
- Citation
- Lahti v. Consensys Software Inc., No. 1:24-cv-00183, ECF No. 44 (S.D. Ohio Aug. 20, 2025) (Hopkins, J.)
- Decided
- August 20, 2025
Summary
Sarah Lahti, proceeding pro se, sued Consensys Software Inc. in the Southern District of Ohio. Her objections to the magistrate judge's report and her reply briefs cited fictitious authority that U.S. District Judge Jeffery P. Hopkins described as having "the hallmarks of text generated by a large language model." The court named three problem citations from her objections: a "Bray v. Lathem Time Co." that exists only from a different court, a "Spira v. J.P. Morgan Chase & Co." that exists only under a different year, citation, and subject, and a "Rogers v. Multiband Corp." the court called "a non-existent case." A fourth real case, McGrew v. VCG Holding Corp., was cited for close to the opposite of what it held. Consensys had separately identified four more fabricated citations in Lahti's reply.
- AI tool:
- Unidentified generative AI (the court found fictitious citations with 'the hallmarks of text generated by a large language model'; no specific tool named)
What sanction did the court impose?
Judge Hopkins adopted the magistrate judge's report and recommendation in full except for its denial of leave to amend, which he granted as to defendant Alphabet. The R&R compelled arbitration of the Consensys claims and dismissed the claims against Alphabet. The court declined to sanction Lahti for the fictitious citations. It warned that if any future filing she submits contains false citations, she "will face severe sanctions similar in nature to those that have been leveled in the cases cited, likely including monetary sanctions."
Why does Lahti v. Consensys Software Inc. matter for law firms using AI?
Lahti is the first of two Hopkins chambers AI-citation orders in S.D. Ohio within a six-month span. The August 2025 warning in Lahti (severe sanctions, likely including monetary sanctions, for future false citations) was the chambers’ opening posture; the January 2026 Lattimore v. Tri-State order reaffirmed the same warning framework. Together, the two orders show Hopkins’s chambers operating a stable warning regime rather than a true escalation: first-offense pro se litigants get a clearly stated warning that future fabrications will draw monetary sanctions.
For Ohio firms litigating in S.D. Ohio, the chambers pattern is the takeaway. Hopkins is willing to decline sanctions on a first occurrence and instead build a record that supports sanctions on a repeat offense. The Lahti warning language is now part of that record. Defendants in any future Hopkins matter against a pro se filer with AI-fabricated authority should reference the Lahti warning posture in opposing the underlying motion; the court has already telegraphed that a second instance crosses the line into monetary sanctions.
Implications for your firm
Operational steps a firm reading this case may wish to consider documenting. Strategic and rule-application calls belong to your firm's attorneys.
- Track Hopkins chambers in S.D. Ohio; the Lahti warning language ('severe sanctions...likely including monetary sanctions') is the chambers' opening posture and was reaffirmed five months later in Lattimore v. Tri-State (Jan 2026).
- Pro se litigants in employment matters are a recurring source of AI-fabricated authority; firms defending employers should expect to surface fabrications in opposing arbitration motions and motions to dismiss.
- The warning in Lahti is procedurally significant: it gives any future S.D. Ohio matter before Hopkins involving the same plaintiff (or any plaintiff briefed on this warning posture) clean grounds for monetary sanctions on a repeat offense.