They watched over the conduct of the provincial governors, removed the negligent, and inflicted punishments on the guilty.

From all the inferior jurisdictions, an appeal in every matter of importance, either civil or criminal, might be brought before the tribunal of the praefect; but his sentence was final and absolute; and the emperors themselves refused to admit any complaints against the judgment or the integrity of a magistrate whom they honored with such unbounded confidence.

His appointments were suitable to his dignity; and if avarice was his ruling passion, he enjoyed frequent opportunities of collecting a rich harvest of fees, of presents, and of perquisites.
Though the emperors no longer dreaded the ambition of their praefects, they were attentive to counterbalance the power of this great office by the uncertainty and shortness of its duration.
From their superior importance and dignity, Rome and Constantinople were alone excepted from the jurisdiction of the Praetorian praefects.

The immense size of the city, and the experience of the tardy, ineffectual operation of the laws, had furnished the policy of Augustus with a specious pretence for introducing a new magistrate, who alone could restrain a servile and turbulent populace by the strong arm of arbitrary power.

Valerius Messalla was appointed the first praefect of Rome, that his reputation might countenance so invidious a measure; but, at the end of a few days, that accomplished citizen resigned his office, declaring, with a spirit worthy of the friend of Brutus, that he found himself incapable of exercising a power incompatible with public freedom.