Brazil’s Top Court Finds Hidden AI Commands Inside a Legal Appeal
Key Facts
Brazil’s Supreme Court is being tested this month by two very different filings. One hid machine instructions inside a document, the other asks the court to seize private jets.
Justice Cristiano Zanin, a member of Brazil’s Supreme Federal Court, ordered an investigation into hidden artificial-intelligence commands found in an appeal. Conjur, a legal news site, reported the order on 25 September 2026, in the first such case the court has detected.
Why This Matters Beyond Brazil
The Supreme Federal Court, known in Brazil as the STF, is the country’s highest constitutional court. It runs almost entirely on an electronic filing system, so every petition arrives as a digital document.
Courts in many countries are now testing artificial intelligence to sort and summarise those documents. That creates a new risk, because text written for a machine can be hidden from a human reader.
Brazil is a useful early case, since its judiciary digitised earlier and more fully than most. The second filing described below lands in the final days before the general election on 4 October 2026.
It asks the court to search aircraft used by Senator Flávio Bolsonaro, the leading opposition candidate. Both matters sit with the same court, which is already under heavy political pressure from both camps.
Dollar figures in this article use the central bank PTAX selling rate of R$5.1991 per dollar on 25 September 2026. PTAX is the official reference rate published each business day by the Banco Central do Brasil.
What the Court Says It Found
Conjur reported that the hidden passage was written in white type at a reduced size. It ran across two pages of the filing and repeated itself in identical form.
The heading read “argumentos fortes para o conhecimento e provimento do RE”, or strong arguments for granting the appeal. Gazeta do Povo, a centre-right daily, put the hidden block at more than 400 words.
Individual words were deliberately broken up so that automatic checks would miss them, the court found. The passage set out arguments for the appeal, a suggested line of decision and legal provisions to cite.
The court’s own technology unit spotted the text using a detection tool it had built in house. Agência Brasil, the state news agency, said the tool was built to spot malicious interference in filings.
The Case Behind the Appeal
The filing is an extraordinary appeal registered at the court as ARE 1.608.713. It came from a Black civil servant who had entered a post through a racial quota at the MPMG.
The MPMG is the public prosecution service of Minas Gerais, Brazil’s second most populous state. Conjur reported that she was removed after a court found an error in the appointment.
Lower courts ruled against her, and she asked the Supreme Court to reopen the question. Racial quotas in public hiring have been law in Brazil since 2014 and remain politically contested.
On 19 August 2026 Zanin rejected the appeal on settled case law, according to Conjur. That rule bars the court from re-examining facts and evidence already weighed by lower instances.
What Zanin Ordered
Zanin imposed a fine of two monthly minimum wages for breaching the duty of procedural loyalty. Gazeta do Povo put that at about R$3,242 (US$624) at 2026 values.
He also referred the matter to the Federal Public Prosecutor’s Office, which decides on criminal charges. A second notice went to the Brazilian Bar Association, the OAB, which handles lawyer discipline.
The OAB can suspend or strike off a lawyer, but it has announced no decision. The penalty went to the court’s First Panel for a virtual vote that opened on 25 September.
Gazeta do Povo reported that Zanin and Justice Alexandre de Moraes had both voted to apply the fine. Zanin also stated that he had not used artificial intelligence in his own analysis of the case.
The Lawyer’s Answer
Gazeta do Povo named the lawyer as Ramon Oliveira Dias and reported his response. He admitted the tactic and said he accepted “pessoalmente a responsabilidade”, or personal responsibility.
He said his client had no knowledge of what had been inserted in the document. He described himself as “movido pela aflição”, moved by distress, after lower courts declined to examine his arguments.
No court has found that he committed a crime, and the prosecution referral is only a first step. The bar association has not said whether it will open disciplinary proceedings against him.
How Prompt Injection Works
Prompt injection means placing instructions in a document that a language model will read as orders. The text is aimed at the software rather than at the judge or clerk handling the file.
White type on a white page is invisible on screen but still present in the underlying file. Splitting words with stray characters can also defeat simple keyword filters.
Brazilian courts have used automated triage for years, which is why the technique has a target here. The STF has not released the full text of the passage, only a description of it.
A Second Filing Over Jets and a Jailed Banker
On 26 September, Deputy Lindbergh Farias of the Workers’ Party filed a separate request at the court. The Workers’ Party, or PT, is the party of President Luiz Inácio Lula da Silva.
Farias asked the court to search and seize aircraft linked to Daniel Vorcaro and the lawyer Willer Tomaz. Vorcaro founded Banco Master, the lender shut down by the central bank in November 2025.
Arrested in November 2025 and again in March 2026, he remains in pre-trial detention without conviction. Brasil 247 reported that Farias wants flight logs, passenger manifests and onboard system data preserved.
His filing also asks for requests to Anac, the civil aviation regulator, and to the Federal Police. The target is a Legacy 650 jet that carried Senator Flávio Bolsonaro and his family in January 2025.
CNN Brasil, citing the magazine piauí, said the flight ran from Florida to Brasília. The Rio Times reported earlier on a video of Justice Alexandre de Moraes leaving a jet linked to the same banker.
The Other Side of the Jet Story
Flávio Bolsonaro is a senator and the main opposition candidate in the presidential race. He responded on social media that the aircraft belonged at the time to the lawyer Willer Tomaz.
“Ainda bem que na época o avião era de Willer,” he wrote, meaning it was lucky the plane was Willer’s. Tomaz said he does not know Vorcaro and has never met him, CNN Brasil reported.
He said he only learned in April 2026 that a Vorcaro company held a stake in the jet. Tomaz said he offered rides at no cost and without any benefit in return, CNN Brasil reported.
According to piauí, the formal owner was a holding company whose shares were split among three parties. Farias used the phrase “hub financeiro”, a financial hub, to describe the structure, Brasil 247 reported.
That characterisation is his allegation and has not been tested by any court. Neither Flávio Bolsonaro nor Tomaz has been charged in connection with the flights.
What It Means If You Follow Brazil
For lawyers and compliance teams, the prompt case sets a marker on what filings may contain. Expect Brazilian courts to publish rules on artificial intelligence in submissions over the coming months.
For investors, the Banco Master file keeps widening and now touches the presidential campaign directly. Any court order on the aircraft would land inside the final week before the first round.
Readers following the election should treat both filings as claims under examination, not findings. The court has given no date for deciding the search request from Farias.
What Is Not Yet Known
It is not known whether prosecutors will open a criminal case over the hidden passage. The bar association has not said what action, if any, it will take against the lawyer.
The court has not said whether it will screen older filings for the same technique. It is not known which justice will rule on the request to search the aircraft.
Frequently Asked Questions
What is prompt injection in a court filing?
It means hiding instructions in a document so that artificial-intelligence software treats them as orders. In this case the text was written in white type and split up to avoid detection.
What did Justice Zanin decide?
He rejected the appeal in August and fined the lawyer two minimum wages, about R$3,242 (US$624). He also referred the matter to federal prosecutors and to the bar association.
Has anyone been convicted over this?
No. The referral to prosecutors is only a first step, and the bar association has announced no disciplinary decision.
What do the private jets have to do with the court?
A governing-party deputy asked the Supreme Court to order searches of aircraft linked to a jailed banker. He says flights carried Senator Flávio Bolsonaro, who says the plane belonged to a lawyer friend.
Sources: Conjur, the court identifies its first attempted procedural fraud, Gazeta do Povo, Zanin and Moraes vote to fine the lawyer, Agência Brasil, Zanin orders an investigation into the use of AI, Brasil 247, Lindbergh Farias asks for searches of jets linked to Vorcaro, CNN Brasil, piauí report on the Florida flight and the replies, Poder360, Lindbergh moves against Flávio Bolsonaro and Willer Tomaz, Bem Paraná, the order to investigate the forced filing, Banco Central do Brasil, PTAX dollar rate
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