Justice Cristiano Zanin has been selected to report on Senator Alessandro Vieira’s lawsuit asking Brazil’s Supreme Federal Court to order Senate President Davi Alcolumbre to advance a proposed parliamentary inquiry into Banco Master.

Vieira’s case argues that the request has met the constitutional threshold for a Senate commission of inquiry but has remained stalled since it was filed on March 9, 2026. The senator says it ultimately secured 41 signatures—well above the 27 required from the 81-member Senate—and that Alcolumbre has neither read it in plenary nor taken steps to establish the commission.¹

For Vieira, the dispute is not only procedural. The proposed inquiry would examine alleged personal, financial or other links involving Justices Alexandre de Moraes and Dias Toffoli, Daniel Vorcaro, the former owner of Banco Master, and people connected to the bank. He said Supreme Court precedent treats the installation of such a commission as “a right of the minority,” and argued that “serious facts need to be investigated with total transparency, and the Senate is the appropriate place for that.”¹

The action seeks a more specific judicial timetable: Vieira asks the court to require Alcolumbre to read the request within 48 hours of notification, or at the next Senate session, and to begin setting up the body. It also seeks deadlines for party leaders to nominate members; if they do not, Vieira argues that the Senate president should make the appointments.²

The two accounts agree on the central procedural fact: the proposed commission has more than the necessary support and has not progressed in the Senate. They differ in emphasis. Vieira frames the delay as a breach of an enforceable minority safeguard, invoking the court’s earlier ruling on the COVID-19 inquiry, while the case’s requested remedies focus on the mechanics of compelling a reading, nominations and installation.¹

No response from Alcolumbre or the justices named in the proposed inquiry was included in the provided reports. Zanin’s assignment places the dispute before the Supreme Court, which will now consider whether it can require the Senate leadership to act.