Conflict of jurisdiction before the Superior Court of Justice (STJ) to determine which state court should adjudicate an emergency relief action incidental to a public-interest civil action pending in Rondônia, aimed at preventing the enforcement of negotiable instruments in the State of São Paulo that secured the financing of the construction of the hydroelectric power plant whose rupture caused environmental damage. Dismissal of the emergency relief action due to the supervening establishment of the arbitral tribunal, which becomes competent to adjudicate on an emergency relief basis the pertinence of maintaining the enforcement proceedings. Consequent loss of subject matter of the conflict of jurisdiction between the state courts: