Considering the restrictions of the lex Calpurnia and the fact that its author was a conservative, it has been suggested that Piso actually wanted to reinforce the powers of the Senate over the assemblies and the tribunes of the plebs.
Two famous trials of the 130s BC indeed show that prominent politicians such as Metellus Macedonicus and Scipio Aemilianus prosecuted their enemies through the extortion court.
After the first two Punic Wars, the Roman Republic rapidly expanded outside Italy in Sicily, Sardinia and Corsica, Cisalpine Gaul, and Hispania Citerior and Ulterior.
[2][3] For example, in 171 the former consul Marcus Popillius Laenas was tried for having sold in slavery the Statellates, a Ligurian people, but the praetor assigned with the investigation delayed it until the case was dropped.
Galba was an outstanding orator and played on the crowd's emotions by bringing his children to the stage and shedding tears imploring for mercy; touched by his defence, the assembled people rejected Scribonius' bill.
[7] Another tribune of the plebs for 149, Lucius Calpurnius Piso Frugi, wished to solve the problem raised by Galba's case by establishing a permanent criminal court to judge Roman officials.
Michael Crawford suggests that a temporary citizenship could be given to provincials for the time of the trial, but the majority of modern scholars consider that they had to be represented by Roman patrons who acted on their behalf.
In order to explain the lex Calpurnia's mildness, Erich Gruen has suggested that Piso wished to strengthen the power of the Senate over the tribunes of the plebs and the popular assembly.
Indeed, as with the previous ad-hoc courts, a criminal trial started under the lex Calpurnia could not be vetoed by a tribune of the plebs, and its verdict could not be appealed, which therefore massively increased the influence of the senate.
[22] Silanus' trial probably created interest at Rome, and several political groups saw in the lex Calpurnia a powerful weapon to use against opponents.
[24][25] The family links between the Metelli and the Caepiones make it certain that they formed a faction and that their accusation was more motivated by their enmity against Pompeius than the welfare of the Spanish provincials.
[32] As with the previous case, it is probable that the senators who composed the jury did not want to be part of a political feud, albeit Appian tells that Cotta bribed the jurors.
[36][37] The lex Calpurnia was the first of a long series of extortion laws passed in the last century of the Roman Republic, during which the composition of the juries became a divisive political topic.
[39] In 122, the tribune of the plebs Manius Acilius Glabrio passed the lex Acilia repetundarum, as part of the vast program of reforms pushed by Gaius Gracchus.
[47] In 59, Julius Caesar as consul passed the very severe lex Iulia de repetundis which forced into exile guilty officials, and also replaced Sulla's law.