17. C.CalpurniusPiso, was consul B. C. 67, with M'. Acilius Glabrio. He belonged to the high aristocratical party, and, as consul, led the opposition to the proposed law of the tribune Gabinius, by which Pompey was to be entrusted with extraordinary powers for the purpose of conducting the war against the pirates. Piso even went so far as to threaten Pompey's life, telling him, "that if he emulated Romulus, he would not escape the end of Romulus," for which imprudent speech he was nearly torn to pieces by the people. The law, however, was carried, notwithstanding all the opposition of Piso and his party; and when shortly afterwards the orders which Pompey had issued, were not carried into execution in Narbonese Gaul, in consequence, as it was supposed, of the intrigues of Piso, Gabinius proposed to deprive the latter of his consulship, an extreme measure which Pompey's prudence would not allow to be brought forward. Piso had not an easy life in this consulship. In the same year the tribune, C. Cornelius, proposed several laws, which were directed against the shameless abuses of the aristocracy. [CORNELIUS, Vol. I. p. 857.] All these Piso resisted with the utmost vehemence, and none more strongly than a stringent enactment to put down bribery at elections. But as the senate could not with any decency refuse to lend their aid in suppressing this corrupt practice, they pretended that the law of Cornelius was so severe, that no accusers would come forward, and no judges would condemn a criminal; and they therefore made the consuls bring forward a less stringent law (Lex Acilia Calpurnia), imposing a fine on the offender, with exclusion from the senate and all public offices. It was with no desire to diminish corruption at elections that Piso joined his colleague in proposing the law, for an accusation had been brought against him in the preceding year of obtaining by bribery his own election to the consulship.

In B. C. 66 and 65, Piso administered the province of Narbonese Gaul as proconsul, and while there suppressed an insurrection of the Allobroges. Like the other Roman nobles, he plundered his province, and was defended by Cicero in B. C. 63, when he was accused of robbing the Allobroges, and of executing unjustly a Transpadane Gaul. The latter charge was brought against him at the instigation of Caesar; and Piso, in revenge, implored Cicero, but without success, to accuse Caesar as one of the conspirators of Catiline. Piso must have died before the breaking out of the civil war, but in what year is uncertain. Cicero ascribes (Brut. 68) to him considerable oratorical abilities. (Plut. Pomp. 25, 27; D. C. 36.7, 20-22; Ascon. in Cic. Cornel. pp. 68, 75, ed. Orelli; Cic. Att. 1.1, 13, pro Fllcc. 39; Sal. Cat. 49)

He may be the same as the L. Piso, who was judex in the case of Q. Roscius, B. C. 67 (Cic. pro Rose. Corn. 3, 6), and as the L. Piso, who defended Aebutus against Caecina in 75 (pro Cacein. 12).