The fourth speech, supposedly delivered before the Senate, was an intervention in an on-going debate as to the fate of the urban conspirators; Cicero argued in favour of their illegal execution without trial.
[5] The Catilinarian conspiracy was a plot by the patrician senator Lucius Sergius Catilina (known in English as Catiline) to overthrow the Roman republic.
[10][11] In response, the senate passed a decree declaring a tumultus (a state of emergency) and, after receipt of the reports of armed men gathering in Etruria, carried the senatus consultum ultimum instructing the consuls to do whatever it took to respond to the crisis.
[14] But after messages from Etruria connected him directly to the uprising, he was indicted under the lex Plautia de vi (public violence) in early November.
[16] At this time, Cicero then discovered a plot led by one of the sitting praetors, to bring in the Allobroges, a Gallic tribe, to support the Catilinarians.
[19] After a prolonged debate, the Senate, after momentarily being convinced to sentence the men to life imprisonment without trial by Julius Caesar, advised Cicero to have the urban conspirators summarily executed.
[24] Although popular among large portions of the people for having taken decisive action to avoid civil war and suppress the coup attempt, Cicero's legal position came under attack in the coming years.
[26] In consequence, it is still widely remembered and used after more than 2000 years: Quō ūsque tandem abūtere, Catilīna, patientiā nostrā?
[31] The oration's arguments, somewhat cloudy and meandering, are intended more to influence senatorial opinion than argue in favour of any specific course of action or actually advise Catiline.
A more retrospective interpretation of how it would have played c. 60 BC would instead emphasise how Cicero chose to act slowly and deliberatively rather than, as alleged by his political enemies, cruelly and autocratically.
This political isolation is then emphasised when Cicero relates that Catiline sought to place himself into voluntary custody to service his reputation but found nobody willing to take him.
The conclusion of the speech notes that Cicero intends to do nothing compulsory at the moment, justified by rejection of arguments to have Catiline summarily executed (placed in the mouth of an abstract personification of Rome).
This speech was delivered with the intention of convincing the lower class, or common man, that Catiline would not represent their interests and they should not support him.
He asked for nothing for himself but the grateful remembrance of the city and acknowledged that the victory was more difficult than one in foreign lands because the enemies were citizens of Rome.
In his fourth and final published[41] argument, which took place in the Temple of Concordia, Cicero establishes a basis for other orators (primarily Cato the Younger) to argue for the execution of the conspirators.
Although very little is known about the actual debate (except for Cicero's argument, which has probably been altered from its original), the Senate majority probably opposed the death sentence for various reasons, one of which was the nobility of the accused.
While some historians[dubious – discuss] agree that Cicero's actions, in particular the final speeches before the Senate, may have saved the Republic, they also reflect his self-aggrandisement and, to a certain extent envy, probably born out of the fact that he was considered a novus homo, a Roman citizen without noble or ancient lineage.