[1] His precise background is unclear: It is unknown if he was related to the jurist and near-contemporary Servius Sulpicius Rufus, and, like him, he might not have been a patrician, despite their matching family names.
[5] In 95 BC, Sulpicius, with the encouragement and approval of the nobility, led an eloquent but ultimately unsuccessful prosecution of a former tribune of the plebs, Gaius Norbanus.
[8] To that end, Drusus as tribune had proposed several ambitious reforms which included the transfer of the state courts from the equestrian class to the Senate, the granting of full citizenship to Rome's restive non-citizen allies across Italy, and distribution of land and grain to the poor.
[15] The outbreak of the Social War was followed by several politically motivated prosecutions as part of the equestrian class's reaction to Drusus's legislative proposals.
One tribune, Varius, established a commission to prosecute Drusus's supporters on the charge that their attempts to appease the Italian allies with promises of citizenship had encouraged them to revolt.
[19][i] Soon afterwards Sulpicius declared in favour of Gaius Marius and the populares, a move considered to be a surprising volte face by contemporaries: Cicero, for instance, remarks that 'the popular breeze carried Sulpicius, who had set out from an excellent position, further than he wished'[22] He was deeply in debt, and it seems that Marius had promised him financial assistance in the event of his being appointed to the command in the Mithridatic Wars, to which Sulla had already been appointed.
To secure the appointment for Marius, Sulpicius brought in a franchise bill by which the newly enfranchised Italian allies and freedmen would have swamped the old electors.
The proposals of Sulpicius became law, and, with the assistance of the new voters, the command was bestowed upon Marius, at the time a privatus holding no elected office.
Marius managed to escape to Africa, but Sulpicius was discovered in a villa at Laurentum and put to death; his head was sent to Sulla and exposed in the forum, and his laws annulled.