Brazil's Supreme Court is giving embattled President Dilma Rousseff a major victory against attempts to remove her from office.

The court has annulled an opposition-leaning impeachment commission that would kick off the proceedings in the lower house. A new group of lawmakers for the commission must be selected.

The ruling finds irregularities in the way the impeachment commission election was formed. The justices also say the Senate has the right to halt the impeachment process even if the full lower house approves it.

The decision late Thursday is another blow to key impeachment advocate, speaker Eduardo Cunha. He made all of the decisions overruled by the court and also faces corruption and obstruction of justice charges of his own.