AI Regulation Tracker / Court ruling
Brazil's STJ excludes AI-generated report as criminal evidence
In two decisions this spring, Brazil's Superior Tribunal de Justiça held that AI-generated material is not self-authenticating and that the duty to verify it stays with the professional who signs the filing.
Brazil's highest court for non-constitutional matters has put two markers down on how artificial intelligence may and may not be used in criminal justice, and both point the same way: the human who signs the document answers for what the machine produced.
The evidence ruling
In a decision reported in April 2026, the Fifth Panel of the Superior Tribunal de Justiça (STJ) excluded a report generated by artificial intelligence from a criminal case, finding it did not meet the standard of reliability required of evidence. The matter arose from a racial-insult prosecution in which an AI-produced document was offered to establish what had been said, even though the official forensic examination did not confirm the disputed word in the audio.
The court's reasoning, as reported, turned on reliability rather than a blanket ban. Generative systems work from statistical patterns and probabilities, the panel noted, and can output plausible-sounding material that is simply wrong. Because that kind of output cannot be traced to a verifiable method or tested for error the way a forensic examination can, it does not carry the minimum reliability that the criminal process demands of evidence. On that basis the document was ordered removed from the record. Brazilian legal commentators have described the ruling as the STJ's first substantive position on generative AI as a means of proof in criminal proceedings, and have read it as a reliability test rather than a prohibition: the question is not whether a tool was used, but whether the resulting material can be independently confirmed.
The lawyer referral
The second signal came in a separate matter reported in May 2026, when an STJ minister found that a habeas corpus petition filed for a drug-trafficking defendant contained citations to decisions that did not exist. The minister described the pattern as an AI "hallucination," where a generative tool fabricates references that look authentic, and referred the lawyer to the Ordem dos Advogados do Brasil (OAB) so the bar could assess the conduct and decide on any discipline.
Taken together, the two decisions frame a single principle. AI-generated material is not self-authenticating, and the responsibility for checking it stays with counsel. As Brazilian courts have put it in the related line of cases, presenting a filing in court is an act reserved to the lawyer, who is also responsible for its content. That framing matters because it forecloses the most common defense heard when fabricated citations surface: that the error came from a tool or an assistant. In the courts' view the signature on the filing is the certification, and it cannot be delegated to software.
What it does not do
Neither decision bans AI from legal work, and neither creates a new statute. They are judicial rulings on specific facts, not a code of conduct, and they do not spell out an approved workflow or a safe-harbor procedure. What they establish is a standard of accountability: the tool's output does not carry its own credibility into the record, and blaming the software, or an assistant, does not transfer the professional's duty to verify. A lawyer who files fabricated authority remains exposed regardless of how the text was produced. Nor do the rulings set a monetary penalty or a fixed procedure for the bar to follow; the OAB referral hands that judgment to the disciplinary body, which decides independently what, if anything, follows. The practical takeaway is narrower and firmer than a ban: use the tools, but confirm the output.
Why a US reader should care
The STJ line tracks a converging global standard rather than a national quirk. It mirrors the United States sanction line that began with Mata v. Avianca, where a federal court penalized lawyers for citing cases invented by a chatbot, and it follows Brazil's own labor court, the Tribunal Superior do Trabalho, which fined a company and its lawyer and referred the matter to the OAB over fabricated precedents. Colombia's high court has annulled a decision on similar grounds. For US firms with Brazilian operations or co-counsel, the practical message is the same one now emerging in their home courts: judges expect the person signing a filing to have personally certified that every AI-assisted citation and analysis is real. The safest reading is that this is where multiple jurisdictions are heading at once.
Frequently Asked Questions
What did Brazil's STJ actually decide about AI evidence?
In a decision reported in April 2026, the STJ Fifth Panel excluded an AI-generated report from a criminal case, holding it lacked the minimum reliability required of evidence and ordering it removed from the record. The ruling is reported as the court's first on generative AI as proof in criminal matters.
Who is affected by these rulings?
Lawyers, litigants, and expert witnesses who use AI tools to draft filings or generate analyses in Brazilian proceedings. The clear operational burden falls on the professional who signs the document, who must verify AI output before it is submitted.
Does this ban lawyers from using AI in Brazil?
No. Neither decision prohibits AI. They hold that AI output is not self-authenticating and that the duty to verify it, against primary sources, remains with counsel. A lawyer who files fabricated authority is exposed regardless of how it was generated.
How does this compare to the US position?
It aligns with the US sanction line that began with Mata v. Avianca and with Brazil's own labor-court ruling, all of which hold lawyers personally accountable for AI-fabricated citations. The pattern suggests a converging international standard rather than an outlier.
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Informational analysis for working professionals, not legal advice. Confirm how any rule applies to your situation with qualified counsel.