He was also known for his trial for public violence (de vi publica) in March 56 BC, when Cicero defended him in the extant speech Pro Caelio, and as both recipient and author of some of the best-written letters in the ad Familiares corpus of Cicero's extant correspondence (Book 8).
He was successfully defended by Crassus and, more famously, Cicero, whose speech Pro Caelio argued that the prosecutor, Atratinus, was being manipulated by Clodia to get revenge on Caelius for an affair gone wrong.
[4] During this period, he wrote a series of witty and informative letters to Cicero, who was serving as proconsul of Cilicia at the time.
However, when his proposed program of debt relief was opposed by the Senate and he was suspended from office, he joined in a rebellion against Caesar which was quickly crushed.
[9] In Caelius in 58, Catullus seems to expect a sympathetic ear as he bewails Lesbia's sexual profligacy; the former is an invective that taunts Rufus for bodily offensiveness that drives away women.
A flamboyant, witty, ambitious and quarrelsome character,[10] Caelius attracted much attention from the minor historian Velleius Paterculus in the following century.