Brazil's Supreme Court voted unanimously Thursday to allow corruption charges against a key congressional leader in a step that could weaken efforts to impeach President Dilma Rousseff, according to AP. All 10 justices at the session voted to proceed with charges against Eduardo Cunha, the head of the lower house of Congress who is accused of taking $5 million in bribes involving a contract by state oil company Petrobras. The 11th justice was out of the country. Under Brazilian law, charges against federal congressmen and other top government officials can be filed and judged only by the Supreme Court. Thursday's decision marked the first time the Supreme Court has authorized charges in connection with the wide-ranging "Car Wash" investigation into corruption at Petrobras. Cunha is one of the biggest names implicated in the scandal, which prosecutors allege involved billions of dollars in bribes. He is also a sworn enemy of Rousseff, having authorized the opening of impeachment proceedings against her late last year over allegations she violated fiscal responsibility laws. Analysts said the Supreme Court's move could undermine the impeachment effort.