The institutional stability of Brazil’s Supreme Federal Court (STF) is under severe strain after the court’s President, Edson Fachin, was forced to intervene in a spiraling conflict between two of its most prominent justices, André Mendonça and Alexandre de Moraes. The crisis erupted over Mendonça's unilateral decision to make public a Federal Police report from the ongoing ‘Master Case’ investigation, which details messages from a disgraced former banker, Daniel Vorcaro, that appear to show a close relationship and sought intervention from Justice de Moraes. The explosive revelations—and the public release of the report—prompted Justice de Moraes to formally request an investigation into Justice Mendonça for alleged abuse of authority and selective conduct, pushing the infighting to a head.