Scaurus may have been among those in Orestes' staff who were offended by Gracchus' successes in obtaining supplies from the Sardinian natives, as well as grain from the Numidian king Micipsa.
In 124, Scaurus possibly denounced Gracchus before the censors for having left his post early in order to run for the tribunician elections for 123.
[25][26] Before the Jugurthine War (112–106 BC), he was sent as envoy to Numidia with a demand for Jugurtha to cease hostilities against the Numidian king Adherbal.
[32] Bates argues that Bestia and Scaurus more likely granted Jugurtha a truce in exchange for reparations and a diplomatic settlement, a choice reflecting Roman military weakness after the defeat in the Battle of Noreia in 113 BC.
[33] When the settlement became known in Rome, the tribune Gaius Mamilius Limetanus embarked on "a general assault upon the nobility" in 109 BC.
However, when Drusus suddenly died during their year of office, Scaurus was forced against his will to abdicate his censorship, only relenting from the position when tribunes ordered him to be dragged off to prison.
[39] In 104 BC, Scaurus became responsible for Rome's grain supply, the cura annonae; his appointment was at the expense of Lucius Appuleius Saturninus, at the time a quaestor.
[42] Bates speculates that Scaurus contributed to the harshness[b] of the Mamilian commission's sentences, but admits there is no direct evidence thereof.
[42] In 104 BC, after Gnaeus Domitius Ahenobarbus – one of the tribunes of the plebs – was not co-opted into the college of augurs, he sued Scaurus.
However, "[Ahenobarbus'] sense of honour made him unwilling to use the evidence that one of Scaurus' own slaves offered to provide" and the trial resulted in acquittal.
[43] Scaurus led the opposition against the popularis tribune Gaius Norbanus's targeting of Quintus Servilius Caepio (consul 106 BC) after the Caepio's refusal as proconsul to cooperate with then-consul Gnaeus Mallius Maximus, leading to the catastrophic defeat at Battle of Arausio in 105 BC.
[50][51][8] While "it is possible... to over-emphasise this fact... it probably devolved upon the princeps senatus to initiate action in matters of such import", Scaurus also did seem to have "nurtured an especially vigorous personal antipathy towards Saturninus".
[50] The mission likely included Gaius Marius – travelling on the pretext of fulfilling a vow to magna mater – but more likely to investigate Mithridates VI's campaigns in Cappadocia without arousing suspicion.
[53] Following the mission, the senate dispatched Quintus Mucius Scaevola Pontifex and Publius Rutilius Rufus to Asia in a successful administration of the province.
[54][55] A few years later in 92 BC, Lucius Cornelius Sulla also was dispatched east as propraetor in Cilicia, where he contested Mithridates' advances into Cappadocia.
[48] He also supported the lex Licinia Mucia, a law to investigate Italians usurping the privileges of Roman citizens,[48] likely in a move to buttress the senate's position in the state.
[57] In 92 BC, Scaurus was probably involved in the defence of Publius Rutilius Rufus, whose honest governance during his time as a legate in Asia province had aroused the enmity of the equites.
[61] Alongside Lucius Licinius Crassus, Scaurus was Drusus' main conservative champion and helped pass his extensive legislative programme.
After Drusus' assassination and the outbreak of the Social war, Scaurus was prosecuted in 90 BC by tribune Quintus Varius Severus.
Cicero in particular was a keen admirer, and once commented that "almost the whole world was ruled by his nod" (cuius nutu prope terrarum orbis regebatur).
Sallust claims that Scaurus accepted bribes from the Numidian king Jugurtha, and calls him "a noble full of energy, a partisan, greedy for power, fame, and riches, but clever in concealing his faults" (homo nobilis impiger factiosus, avidus potentiae honoris divitiarum, ceterum vitia sua callide occultans).
After his death, the turmoil of the civil wars of Cinna and Sulla would submerge the prestige and authority beneath the power of the army.