The younger Marcus Livius Drusus, son of Marcus Livius Drusus, was tribune of the plebeians in 91 BC. In the manner of Gaius Gracchus, he set out with comprehensive plans, but his aim was to strengthen senatorial rule. He removed the jury courts from the jurisdiction of the Equestrian in retaliation for their unjustified condemnation of Publius Rutilius Rufus in 92 BC. To gain support from the plebeians he set up a commission to grant them more land, both around Rome and in new colonies (which was one of only two that was approved by the Senate during the late republic,) and reduced the price of grain. Up to this point Drusus managed to have the support of many of the leading senators including Marcus Aemilius Scaurus. However, Drusus wanted to grant citizenship rights to the Italian allies. This was vehemently opposed by many, he gradually lost support from the Senate, the equites, the Roman population who did not want the Italians to become citizens, and wealthy Italian landlords who did not want to lose their land. In retaliation for his proposal to grant citizenship to the Italian allies, his previous bills were declared invalid, and he was soon assassinated. Soon after his assassination, the Italian allies revolted starting the Social War of 91-88 BC.

His adopted son was Marcus Livius Drusus Claudianus, father of the Empress Livia.