Brazilian court fines lawyers over hidden AI prompt in court filing

A labor court in Brazil has fined two lawyers after finding hidden text in their court filing designed to trick the court's AI tools. A professor from the University of Brasília shared the ruling online. The hidden text, written in white on a white background, was invisible to the eye. Once the font color was changed, it told the AI to only skim the filing, not question its content, and ignore all other instructions. This trick is known as prompt injection. Since the defendant never responded, the plaintiff won by default, so the trick did not work. Still, the court said the act harmed the dignity of justice. The two lawyers were fined 10% of the claim amount, about $16,000, and reported to the state bar association. This was not the first case. Earlier, another party hid prompts in their documents, which a clerk caught due to odd spacing. A state judge was also accused of using AI to write full rulings, but a federal court said she had judicial immunity.