At the beginning of his year of office (Dec. 67) he succeeded in getting a law passed (de libertinorum suffragiis), which gave freedmen the privilege of voting together with those who had manumitted them, that is, in the same tribe as their patroni; this law, however, was almost immediately declared null and void by the senate. Both parties in the state were offended by the law, and Manilius endeavoured to secure the support of Pompey by proposing to confer upon him the command of the war against Mithridates VI of Pontus with unlimited power. The proposal was supported by Cicero in his speech, Pro lege Manilia, and carried almost unanimously. Manilius was later accused by the aristocratical party on some unknown charge and defended by Cicero. He was probably convicted, but nothing further is heard of him.