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 p628  Imperium

Article by George Long, M.A., Fellow of Trinity College
on pp628‑630 of

William Smith, D.C.L., LL.D.:
A Dictionary of Greek and Roman Antiquities, John Murray, London, 1875.

IMPE′RIUM. (Gaius, IV.103), when making a division of judicia into those Quae Legitimo jure consistunt, and those Quae Imperio continentur, observes that the latter are so called  p629 because they continue in force during the Imperium of him who has granted them. Legitima judicia were those which were prosecuted in Rome or within the first miliarium, between Roman citizens, and before a single judex. By a Lex Julia Judiciaria, such judicia expired, unless they were concluded within a year and six months. All other judicia were said Imperio contineri, whether conducted within the above limits before recuperatores, or before a single judex, when either the judex or one of the litigant parties was a peregrinus, or when conducted beyond the first miliarium either between Roman citizens or peregrini. From this passage it follows that there were judicia quae Imperio continebantur, which were granted in Rome; which is made clearer by what follows. There was a distinction between a judicium ex lege, that is, a judicium founded on a particular lex, and a judicium legitimum; for instance, if a man sued in the provinces under a lex, the Aquilia for example, the judicium was not legitimum, but was said Imperio contineri, that is, the Imperium of the praeses or proconsul, who gave the judicium. The same was the case if a man sued at Rome ex lege, and the judicium was before recuperatores, or there was a peregrinus concerned. If a man sued under the praetor's edict, and consequently not ex lege, and a judicium was granted in Rome and the same was before one judex and no foreigner was concerned, it was legitimum. The judicia legitima are mentioned by Cicero (Pro Rosc. Com. 5; Or. Part. 12); but it may perhaps be doubted if he uses the term in the sense in which Gaius does. It appears then, that in the time of Gaius, so long as a man had jurisdictio, so long was he said to have Imperium. Imperium is defined by Ulpian (Dig. 2 tit. 1 s3) to be either merum or mixtum. To have the merum Imperium is to have "gladii potestatem ad animadvertendum in facinorosos homines," a power that had no connection with jurisdictio: the mixtum Imperium is defined by him as that "cui etiam jurisdictio inest," or the power which a magistrate had for the purposes of administering the civil (not criminal) part of the law. It appears then that there was an Imperium which was incident to jurisdictio; the but the merum or pure Imperium was conferred by a lex (Dig. 1 tit. 21 s1). The mixtum Imperium was nothing more than the power necessary for giving effect to the Jurisdictio. There might therefore be Imperium without Jurisdictio, but there could be no Jurisdictio without Imperium. Accordingly, Imperium is sometimes used to express the authority of a magistratus, of which his Jurisdictio is a part (Puchta, Zeitschrift für Gesch. Rechtswissenschaft, vol. X p201).

Imperium is defined by Cicero (Phil. V.16) to be that "sine quo res militaris administrari, teneri exercitus, bellum geri non potest." As opposed to Potestas, it is the power which was conferred by the state upon an individual who was appointed to command an army. The phrases Consularis Potestas and Consulare Imperium might both be properly used; but the expression Tribunitia Potestas only could be used, as the Tribuni never received the Imperium (Liv. VI.37; in Vell. Paterc. II.2, Imperium is improperly used). A consul could not act as commander of an army (attingere rem militarem) unless he were empowered by a Lex Curiata, which is expressed by Livy (V.52) thus:— "Comitia Curiata rem militarem continent." Though consuls were elected at the comitia centuriata, the Comitia Curiata only could give them Imperium (Liv. V.52). This was in conformity with the ancient constitution, according to which the Imperium was conferred on the kings after they had been elected: "On the death of King Pompilius, the populus in the Comitia Curiata elected Tullus Hostilius king, upon the rogation of an interrex; and the king, following the example of Pompilius, too the votes of the populus according to their curiae on the question of his Imperium." (Cic. Rep. II.17). Both Numa (II.13), and Ancus Marcius (II.18), the successor of Tullus, after their appointment as Reges, are severally said "De Imperio suo legem curiatam tulisse." It appears then that, from the kingly period to the time of Cicero, the Imperium, as such, was conferred by a Lex Curiata. On the kingly Imperium see Becker, Handbuch der Röm. Alterthümer, vol. I part II. p314, &c.

The Imperium of the kings is not defined by Cicero. It is declared by some modern writers to have been the military and the judicial power; and it is said that the consuls also received the Imperium in the same sense; and the reason why the Lex Curiata is specially said to confer the Imperium Militare, is that it specially referred to the consuls, and by the establishment of the praetor­ship the jurisdictio was separated from the consul­ship. It may be conjectured that the division of Imperium, made by the jurists, was in accordance with the practice of the republican period: there was during the republican period an Imperium within the walls which was incident to jurisdictio, and an Imperium without the walls which was conferred by a lex curiata. There are no traces of this separation in the kingly period, and it is probable that the king received the Imperium in its full import, and that its separation into two parts belongs to the republican period. The Imperium, which was conferred by a lex under the republic, was limited, if not by the terms in which it was conferred, at least by usage: it could not be held or exercised within the city. It was sometimes specially conferred on an individual for the day of his triumph within the city; and, at least in some cases, by a plebiscitum (Liv. XXVI.21, XLV.35).

The Imperium was as necessary for the governor of a province, as for a general who merely commanded the armies of the republic, as he could not without it exercise military authority (rem militarem attingere) (see Caes. B. C. I.6). So far as we can trace the strict practice of the Roman constitution, military command was given by a special lex, and was not incident to any office, and might be held without any other office than that of imperator. It appears that in the time of Cicero there were doubts as to the necessity of the lex in some cases, which may have gradually arisen from the irregular practices of the civil wars, and from the gradual decay of the old institutions. Cicero, in a passage which is not very clear (Ad Fam. I.9), refers to a Cornelia Lex according to which an individual who had received a Province ex Senatus-consulto thereby acquired the Imperium, without the formality of a Lex Curiata.

The Imperium (merum) of the republic appears to have been (1), a power which was only exercised out of the city; (2) a power which was  p630 specially conferred by a Lex Curiata, and was not incident to any office; (3) a power without which no military operation could be considered as done in the name and on the behalf of the state. Of this a notable example is recorded in Livy (Liv. XXVI.2), where the senate refused to recognise a Roman as a commander because he had not received the Imperium in due form.

In respect of his Imperium, he who received it was styled imperator (αὐτοκράτωρ): he might be a consul or a proconsul. It was an ancient practice, observes Tacitus (Ann. III.74), for the soldiers of a victorious general to salute him by the title of imperator; but in the instance referred to by Tacitus, the Emperor Tiberius allowed the soldiers to confer the title on an individual who had it not already, while under the republic the title as a matter of course was given with the Imperium; and every general who received the Imperium was entitled to the name of imperator. After a victory it was usual for the soldiers to salute their commander as imperator, but this salutation neither gave nor confirmed the title. Under the republic, observes Tacitus, there were several imperatores at the same time: Augustus granted the title to some; but the last instance, he adds, of the title being conferred was in the case of Blaesus, under Tiberius. There were, however, later instances. The assumption of the praenomen of imperator by Julius Caesar (Suet. Caes. c76) was a usurpation; or it may have been conferred by the senate (Dion Cassius, XLIII.44). Under the republic the title came properly after the name; thus Cicero, when he was proconsul in Cilicia, could properly style himself M. Tullius Cicero Imperator, for the term merely expressed that he had the Imperium. Tiberius and Claudius refused to assume the praenomen of Imperator, but the use of it as a praenomen became established among their successors, as we see from the imperial coins. The title Imperator sometimes appears on the imperial medals, followed by a numeral (VI, for instance), which indicates that it was specially assumed by them on the occasion of some great victory; for though the victory might be gained by their generals, it was considered to be gained under the auspices of the Imperator.

The term Imperium was applied in the republican period to express the sovereignty of the Roman state. Thus Gaul is said by Cicero (Pro Font. 1) to have come under the Imperium and Ditio of the Populus Romanus; and the notion of the Majestas Populi Romani is said to be "in Imperii atque in nominis populi Romani dignitate." (Cic. Or. Part. 30). Compare the use of Imperium in Horace, Od. I.37, III.5.

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