6. Cognitio - Investigation by Magistrates or Officials
Cognitio was the term used for a criminal investigation by a magistrate or magistrates assisted by a consilium of advisers. This procedure, as has been seen earlier, existed before the creation of permanent criminal tribunals, and it was still employed at Rome from time to time during the late Republic to deal with special offences, such as the quaestio Mamilia about the receipt of bribes from King Iugurtha in 110 BC.100 It was also the
regular form taken by a criminal trial before a provincial governor in person, assuming that he did not refer the matter to one of the courts in the province.
When the Roman emperor, by virtue of his proconsulare imperium maius in the Roman empire, became the ultimate source of justice for Rome’s allies and subjects, cognitio was the form taken by cases referred to him directly or on appeal. Augustus also, as we have seen, exercised this form of justice at first instance over certain cases from Rome and Italy, although the practice was to arouse disquiet among the elite when later followed by Claudius. In the longer run, to an increasing extent cognitio came to replace the operations of the permanent criminal tribunals in respect of cases arising at Rome or in Italy.101 However, this was not, and could not have been, achieved simply by multiplying trials before the emperor in person, but required the delegation of judicial powers to magistrates or other appointees. As under the Republic, cognitio was a convenient way of proceeding against mass offences and also permitted the investigation of behaviour, believed criminal, which did not fall neatly within the categories of offence listed in the statutes governing the permanent criminal tribunals.102 Moreover, the denouncing of an offender to a magistrate for judicial investigation required less action and commitment than the procedure for accusation before a permanent tribunal and would have been less likely to deter those of inferior status who lacked suitable patrons.It is hard to establish how soon cognitio by subordinates of the emperor developed at Rome and how quickly and completely it supplanted the quaestiones perpetuae.
The praefectus urbi was originally devised by Augustus as a kind of minister of public security, hence his command of the urban cohorts.103 This was the situation in Tiberius’ reign, but by AD 61 under Nero the prefect’s jurisdiction in certain criminal cases was so well established that a man was condemned to exile by the senate for bringing accusations before a quaestio perpetua in order to avoid their being heard by the prefect of the city, his plan being to mishandle the prosecution in the quaestio and so prevent the defendant being tried again - in Roman terms a form ofpraevaricatio.104 The poet Statius’ praise of Rutilius Gallicus, prefect under Domitian in about AD 90, suggests that the latter’s jurisdiction was then especially exercised over common criminals who violently disturbed the peace, whether at Rome or elsewhere in Italy — men who might be imprisoned or flogged.105 However, under Trajan, Pliny sat as assessor to the prefect in a case where two promising young orators were speaking on either side, which suggests a defendant of some status and importance, perhaps accused of murder or violence106 By the time Ulpian wrote his work On the Duties of the Prefect of the City in the early third century, the prefect had become a universal criminal magistrate for cases up to 100 miles from the city of Rome with powers of punishment appropriate for persons of high rank.107Limited jurisdictions inferior to that of the city prefect were acquired by the prefect of the watch (praefectus vigilum) in matters relating to fires and theft,108 and perhaps by the prefect of the corn-supply (praefectus annonae),IO9 in order that the latter could determine whether a fine for corn-hoarding was appropriate. More important in the long term were the judicial powers granted to the prefects of the guard (praefecti praetorio).110 The first securely attested to have acted as a judge at Rome is Q.
Marcius Turbo under Hadrian.111 Later, in the reign of Marcus Aurelius we find on a well-known inscription from Saepinum the prefects Bassaeus Rufus and Macrinius Vindex threatening the local magistrates with an inquiry and punishment because of their interference with flocks belonging to the imperial treasury. 112 Unfortunately we have no idea of the scope of the praetorian prefects’ judicial activity before the late empire, when it was wide-ranging.It is generally assumed that cognitio (investigation by magistrates) had supplanted the operations of the criminal tribunals at Rome by the epoch of the great classical jurists at the beginning of the third century AD. However, due to the scarcity of evidence it may be better to leave the question open. The younger Pliny certainly knew of a praetor in charge of a quaestio perpetua. 113 In the third century AD Paul’s prescription of the written form to be used for accusations for adultery had just two alternative addressees - a praetor (who in this era can only have been the man in charge of the criminal tribunal) or a proconsul (the authority in a province). 114 Hence, we should assume that the quaestio de adulteriis was still functioning. As for the alleged 3,000 accusations for adultery arising from Septimius Severus’ legislation that the historian Dio Cassius claims to have seen inscribed on the album when consul in about AD 205,115 it seems as likely that these were originally addressed to the appropriate praetor as to one of the prefects or the emperor himself (whether Dio was considering them for possible hearing in the senate or not).