President of the section says that hidden commands in the petition tried to interfere in judicial analysis by AI; case is being processed in the Rondônia Court
The (Brazilian Bar Association in Rondônia) cautiously dismissed on Monday (June 1, 2026) a lawyer investigated for inserting hidden commands in a judicial petition to try to influence AI (artificial intelligence) systems used in the analysis of processes. Read (PDF — 10 MB).
The measure was determined by the president of the section, after a decision by the Rondônia Court to recognize the practice of prompt injection in an action being processed in the 2nd Civil Court of Porto Velho. The lawsuit was filed by a patient against Sul América Serviços de Saúde to force the plan to cover medical procedures.
In an interview with Poder360Nogueira stated that the conduct is serious because the attempt to convince the court process must occur in a clear and transparent manner. According to him, the problem is not in the use of AI by lawyers, but in the insertion of hidden commands designed to interfere with the analysis of the process and the judicial decision.
“The lawyer is there to influence the judge in a decision, but not everything goes to reach that result”these.
The president of OAB-RO stated that he became aware of the case after the court decision began to circulate in WhatsApp groups. According to him, when consulting the process at the PJe, he found that the defendant’s objection pointed out the existence of the prompt injection in the initial petition and that the judge had recognized the practice.
“When I saw that, I understood the seriousness of this conduct and I think that the Order, as a regulator of the profession, has a very important role in establishing the ethical parameters of these challenging times”he stated.
WHAT IS PROMPT INJECTION?
Prompt injection is a technique used to insert commands into texts, files or pages with the aim of interfering with the behavior of artificial intelligence systems. In a judicial process, the risk is that commands hidden in a petition try to guide the reading made by AI tools used by lawyers, civil servants or magistrates.
In the decision, judge Danilo Augusto Kanthack Paccini stated that he identified “severe drooping of prompt injection” in the initial petition. According to the judge, commands invisible to the human eye were inserted, in an extremely small font and in white, after the lawyers’ signature.
The judge said that the hidden command sought to guide any AI system to classify the medical procedures discussed in the action as urgent, reinforce the probability of the plaintiff’s right and conclude that emergency relief was necessary.
HIDDEN COMMANDS
The judge stated that the conduct was not limited to generally favoring the author’s thesis. According to him, the command was also trying to direct the analysis towards a specific conclusion about the risks of postponing medical procedures discussed in the process.
For the judge, the practice does not constitute a mere formal irregularity, but an attempt to compromise the reliability of the documentary analysis and the contradiction. He stated that the use of hidden commands sought to artificially influence any analysis carried out by an AI system.
Nogueira said that the central point of the case is the hidden nature of the commands. According to him, law exists to influence judicial decisions through arguments, but this influence needs to be exposed to the other parties and the judge.
“In the fair game, I put my argument, the other party puts theirs, the magistrate decides. Here, in the prompt injectionnot even the magistrate can exercise his conscience to weigh it, and the other party cannot contradict the argument”he stated.
According to the president of OAB-RO, the practice circumvents the contradiction, the broad defense and the very logic of the judicial process.
PRECAUTIONARY LEAVE
The judge imposed a fine for bad faith litigation on the plaintiff, but did not directly punish the lawyer in the disciplinary field. In the decision, he stated that any ethical investigation would be the responsibility of the OAB and ordered the issuance of a letter to the Rondônia section, with a copy of the initial petition and the decision.
Nogueira said that he acted ex officio even before formally receiving the letter from the Court. According to him, he decided to use a prerogative recognized by the Federal Council of the OAB for sectional presidents in exceptional situations to preventively suspend the lawyer from professional practice.
The OAB-RO reported that it also initiated an ethical-disciplinary procedure to investigate the facts. The precautionary measure does not represent a definitive judgment or anticipation of punishment. The case will continue with a guarantee of adversarial proceedings, full defense and due legal process.
According to Nogueira, only one of the lawyers who appeared in the piece was removed because only he digitally signed the petition. The president of the section stated that there was no proof, at the time of the precautionary decision, that another lawyer mentioned in the document had contributed to the conduct.
AI IN THE JUDICIARY
For Nogueira, the case shows that different institutions will have to act in defining parameters for the use of artificial intelligence in the Justice system. He stated that the OAB must regulate the conduct of lawyers, the CNJ (National Council of Justice) must deal with the use of technology in the Judiciary and Congress must discuss topics that depend on law.
“It is impossible for us to create a regulation that solves the problems that will happen next week, next month or next year. I think everyone has to act in a coordinated way”these.
The president of OAB-RO stated that artificial intelligence can be used legitimately by lawyers, including for research, organizing arguments and supporting the preparation of documents. The limit, according to him, lies in the use of hidden mechanisms to artificially alter the formation of a decision.
“Technology changes. The fundamental values of law remain the same: good faith, procedural loyalty, transparency and commitment to Justice”he stated.
ELECTORAL RISK
Nogueira also said that the limits of the use of AI must be tested in the 2026 elections. For him, the technology can be used for good or bad, and the Electoral Court will have to decide specific cases on the subject.
According to the lawyer, the resolution of the (Superior Electoral Court) on represents an initial effort, but the combination of technological advances and human creativity should lead to the standard being tested intensively during the electoral process.
“AI is a tool. As a tool, it can be used for good or for evil. If we, as an organized society and as a State, are not willing to regulate, it is a very dangerous weapon”these.
