The lex Calpurnia de repetundis ("law of Calpurnius for the recovery of property") was a Roman law sponsored in 149 BC by the tribune of the plebs Lucius Calpurnius Piso. It established the first permanent criminal court in Roman history, in order to deal with the growing number of crimes committed by Roman governors in the provinces. The lex Calpurnia was a milestone in both Roman law and politics.
Before the lex Calpurnia, criminal cases were investigated by ad-hoc courts before one of the legislative assemblies, which were subject to emotion and rhetorical devices. Instead, the permanent court created by this law was presided by a praetor with a jury composed of senators, who therefore had to judge their peers. It appears that the scope and the penalty were very limited, as officials could only be sued for extortion, and they could only be forced to give back what they had stolen, without additional compensation. Moreover, provincial claimants had to be represented by a Roman patron at the court. 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.
However, the lex Calpurnia came to be used as a political weapon between senatorial factions. 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. Political interests then led to repetitive amendments of the lex Calpurnia, notably by increasing the penalties and altering the composition of the jury. The backbone of the law nevertheless remained in place well into the Roman Empire.