Garces v. Hernandez: The Fifth Circuit’s Express Admonition on AI-Generated Citations and the Unyielding Reach of Res Judicata

1. Introduction

Garces v. Hernandez (No. 25-50342, 5th Cir. Aug. 19, 2025) is a concise, unpublished decision that nevertheless carries outsized doctrinal and practical significance. The case centers on Matthew Andrew Garces, a prolific pro se litigant who—after losing a state-court action arising from his eviction by WoodSpring Suites—re-filed identical claims in federal court. When the district court dismissed on res judicata grounds, Garces appealed.

The Fifth Circuit affirmed but, more importantly, issued a pointed warning about the misuse of generative artificial intelligence (AI) to fabricate authorities. This admonition is notable because it marks one of the first federal appellate opinions to discuss AI-generated citations and articulate potential sanctions for unverified AI output.

2. Summary of the Judgment

Holding: The panel affirmed dismissal because a final Texas county-court judgment barred Garces’s federal suit under Texas claim-preclusion rules and 28 U.S.C. § 1738 (Full Faith and Credit Act).
Key ancillary ruling: The court warned that citing fictitious or “hallucinated” cases—apparently generated by AI—may violate Federal Rules of Appellate Procedure 32 (signature/verification) and 38 (frivolous appeals), exposing litigants to sanctions.
Sanctions warning: Given Garces’s 28 additional pro se filings and prior cease-and-desist orders, the court reiterated that repetitive or abusive litigation could lead to monetary sanctions and filing restrictions.

3. Analysis

3.1 Precedents Cited and Their Influence

The panel anchored its decision on well-established doctrines, but each citation served a discrete purpose:

Heller Financial, Inc. v. Grammco Computer Sales, Inc., 71 F.3d 518 (5th Cir. 1996) – Provided the three-part Texas res judicata test (identity of parties, competent jurisdiction, final judgment on the merits) and the principle that state law governs claim-preclusion scope when a state judgment is at issue.
Tafflin v. Levitt, 493 U.S. 455 (1990) – Rebutted Garces’s argument that the county court lacked jurisdiction over federal civil-rights claims, reinforcing the presumption of concurrent state-court jurisdiction absent congressional exclusivity.
Non-existent cases (e.g., Ermine v. Frank, Lenz v. City of Minneapolis) – Cited only by Garces, these “authorities” triggered the court’s AI-citation discussion. Their absence from any reporter underscored the litigant’s breach of duty to verify.

3.2 Legal Reasoning

Analytical Steps:

Identify the governing preclusion law (Texas) via § 1738.
Apply Texas’s three-element test from Heller Financial:
- Identity of parties – same plaintiff and defendants.
- Final judgment – state judgment became final after 30 days with no appeal.
- Same claim/subject matter – Garces admitted the claims overlapped.
Conclusion: All elements satisfied → claims barred.
Reject Garces’s specific arguments:
- County court jurisdictional objections – contradicted by Tafflin.
- Monetary-limit objection – foreclosed; he voluntarily chose that forum.
- Inability to appear – unsupported by any valid authority; even if true, remedy was a state appeal, not a federal do-over.
Address litigation conduct:
- Flagged AI-generated fictitious citations.
- Highlighted pattern of abusive filings; referenced prior cease-and-desist order and potential pre-filing injunction.

3.3 Likely Impact of the Decision

Although unpublished, the opinion resonates in two distinct arenas:

Litigation Ethics & Technology: Garces joins Mata v. Avianca, Inc. (S.D.N.Y. 2023) and a handful of district-court orders in cautioning against unverified AI research. It is the first Fifth Circuit case to
1. explicitly reference “generative artificial intelligence,” and
2. tie the use of AI to potential violations of Fed. R. App. P. 32 & 38.
Expect trial and appellate courts within the circuit to cite Garces when imposing or threatening sanctions for AI-induced misrepresentations.
Claim-preclusion Clarity: The case re-emphasizes that Texas county-court judgments, even in seemingly “small” eviction disputes, carry full res judicata force in federal court. Litigants cannot bypass a lost state case by re-pleading federal civil-rights statutes.
Pro se Filings: The decision fortifies the Fifth Circuit’s willingness to impose filing injunctions on vexatious litigants, providing a roadmap (warning → cease-and-desist → pre-filing injunction → monetary sanctions) that district courts can emulate.

4. Complex Concepts Simplified

Res Judicata (Claim Preclusion): Latin for “a matter judged.” Once a court of competent jurisdiction issues a final judgment on the merits, the same parties cannot relitigate the same claim or any claim arising from the same transaction in a later suit.
Full Faith and Credit Act – 28 U.S.C. § 1738: Requires federal courts to give the same preclusive effect to state-court judgments as the originating state would.
Generative AI “Hallucination”: When an AI tool outputs plausible-sounding but fabricated legal authorities. Lawyers (and pro se litigants) must manually verify every citation.
Fed. R. App. P. 32 & 38: Rule 32: Governs form of briefs and includes signature requirements, implicitly imposing a duty of candor.
Rule 38: Authorizes damages and costs for frivolous appeals.

5. Conclusion

Garces v. Hernandez reaffirms two core principles: (1) state-court judgments, however modest the forum, bind subsequent federal litigation under res judicata; and (2) the judiciary will not tolerate the uncritical use of AI that results in fictitious citations. For practitioners, the case is a cautionary tale—verify before you cite, and respect the finality of state judgments. For courts, it supplies fresh authority to sanction litigants (pro se or represented) who misuse technology or engage in repetitive, abusive filings. In the evolving landscape where AI intersects with legal practice, Garces v. Hernandez stands as an early but definitive beacon of judicial expectations and boundaries.