In a landmark court case that pits the state against indigenous people, an international human rights commission has accused Brazil of failing to obey its own constitution and protect ancient tribal territories.
Brazil could be forced to pay damages if it loses the trial in the Inter-American Court of Human Rights, which is hearing evidence from both sides in Guatemala.
"This case could strengthen the fight of indigenous people, who continue to have their rights threatened in Brazil," said Raphaela Lopes, a lawyer at Global Justice, a nongovernmental organization that is supporting the case.