As we observed in Chapter 7, Augustus succeeded with his consummate statecraft in establishing a form of government capable of engendering internal political stabilization and consolidating the Roman imperium. In all his earlier acts, Augustus made a great show of restoring the old republican forms of government. One method for accomplishing this so-called ‘restoration of the Republic’ was acknowledging the authority of the senate and the people, thereby appealing to the prevailing republican instincts held by a large section of the Roman population. Over time, the senate and the people responded by granting him the extraordinary powers he deemed necessary to complete the political reconstruction. In the end, all these powers were consolidated into a form where the individual elements could scarcely be distinguished. Thus, Augustus wielded a power greater than that normally accorded to any republican magistrate, and he virtually became the undisputed master of the state. His successors inherited his powers, but a long interval passed before the new system of government was so thoroughly institutionalized that the blatant exercise of imperial power was completely feasible. The princeps-emperor may be described as a magistrate with a super-imperium, outranking all other magistrates and liberated from the check of the tribune’s veto by assuming the tribunician power himself. The existence of an imperium of this kind naturally had a tremendous influence on the development of the law. Initially, this influence manifested itself indirectly through the manipulation of the old republican institutions. Yet, as the last vestiges of the old regime gradually faded, the emperor became the only living source of law.

Contemporary writers designate the period from Augustus to the middle of the third century AD as the classical period of Roman law. During this period, legislative actions emanated from several sources. As under the Republic, laws existing technically as leges could only be passed by the citizens of Rome gathered in official assembly. Other legal sources developed in republican times included magisterial edicts, legal interpretations by jurists and practices sanctioned by custom. New sources of law were the resolutions of the senate (senatus consulta), and the various categories of imperial decrees (constutitiones principum).

The vested right of the assemblies to enact legislation was maintained as a regular function. Under Augustus and his successors, several important statutes were passed concerning marriage and divorce, the freeing of slaves and matters of legal procedure. However, these measures were all part of imperial policy and expressed the emperor’s will. As the political functions of the assemblies declined rapidly under the new regime, popular legislation became obsolete and ceased to exist at the end of the first century AD.

As we have discerned, the magistrates of the Roman state originally possessed considerable freedom in exercising their imperium. On entering office, each magistrate customarily issued an edict informing citizens how he intended to administer the law. In time, these edicts were established by custom so that a new magistrate would adopt the edict of his predecessors and execute few, if any, changes. These general edicts, especially those issued by the praetor, engendered a new body of law known as magisterial or praetorian law (ius honorarium, ius praetorium). However, from the beginning of the imperial period the productive strength of the magisterial edict dwindled. Magisterial initiatives became increasingly rare with the gradual erosion of the magistrates’ right to alter the edicts on their own authority. Finally, the codification of the ius honorarium during Emperor Hadrian’s reign (AD 130) terminated the edict as a source of new law.

During the first three centuries of the Empire, the most productive element in Roman legal life was the work of the jurists. Roman jurisprudence originated with the priestly college of the pontifices. Since the second century BC, an increasing number of members from the Roman ruling class (nobiles) engaged in jurisprudence without being members of the collegium pontificum and they acquired a great part of the prestige held by the pontificate. The main activities of the jurists were the presentation of opinions on difficult points of law to magistrates, judges and litigating parties (respondere), the drafting of legal documents, such as contracts and wills (cavere) and the guiding of litigants on matters of legal procedure (agere). Besides these practical activities, the jurists were absorbed in two other tasks that notably contributed to the development of law: the writing of legal works (scribere) and the teaching of law (docere). Like the pontiffs, the jurists did not receive any remuneration for their services and only devoted some of their time to law as they were occupied with public life and the pursuit of high offices. However, in the last century of the Republic a group of jurists emerged who actually withdrew from politics to dedicate themselves to law. During the Principate the authority of the jurists was further enhanced. Seeking to initiate a certain indirect control over the jurists, Augustus granted a select group of specially qualified jurists the privilege of presenting legal opinions (ius respondendi) and delivering them with the emperor’s authority (ex auctoritate principis). In the second century AD Emperor Hadrian introduced the rule that if a majority of jurists with the ius respondendi held the same opinion it was binding on the judge – in all other cases, a judge was free to choose between conflicting opinions. At that time, the most distinguished jurists were drawn into the imperial circle and exercised their chief functions as members of the emperor’s administrative apparatus. By playing a direct role in governmental tasks and the central imperial administration of justice, the jurists contributed to the evolution of the new public law for the empire. However, their main interest was still principally focused on private law. Classical jurisprudence absorbed all the legal questions in this field that had arisen in the later republican period. These questions, enriched by the emergence of new issues, were categorized and often adequately answered for the first time. It should be noted that the classical jurists, like their predecessors of the republican period, were essentially practical men concerned with devising correct solutions to concrete questions rather than formulating general principles applicable to all times and all societies. The practical nature of their interests is reflected in their writings, as their major works evolved from legal practice and were composed primarily for legal practitioners. Throughout the Principate, legal development was promoted mainly by the jurists and their achievements essentially facilitated the full realization of the Romans’ genius for law.

In republican times the senate exercised great influence on legislation, although it apparently did not have a formal right to directly enact legislation itself. For all practical purposes, its resolutions (senatus consulta) were treated as valid law and under normal circumstances could not be violated with impunity. Under the Principate, the senatus consultum became an officially acknowledged, and in fact the usually adopted, form of legislation. This situation derived from two factors: first, the senate increasingly embraced the task of guiding magistrates in issuing their edicts; second, by the end of the first century AD the senate had replaced the popular assemblies as the republican element of the constitution and the functions of the statute were assumed by the senatorial resolution. However, from the time of Augustus the senate’s freedom of decision was already subject to the emperor’s power. As a result, the senatorial resolutions became increasingly little more than mere declarations of the emperor’s will.

The crucial factor that distinguishes the imperial era from the preceding age is the emperor’s position and influence in the field of law. In the early Principate, the emperors indirectly achieved their legislative goals through controlled decrees of the senate and enactments of the people’s assemblies. But as imperial power intensified at the expense of the old republican institutions, the emperors started to create new legal rules directly in a number of ways. Imperial legislation was designated the common name of imperial constitutions (constitutiones principis) and assumed diverse forms: administrative orders (edicta); precedent-creating judicial decisions of the emperor in individual cases (decreta); answers to questions of law submitted by officials or private citizens (rescripta); and instructions issued by the emperor to officials in his service (mandata).

During the first two centuries of the Principate, Roman law proliferated in the provinces as a consequence of the Roman citizenship policies and Romanization process. In the western provinces, where native legal traditions were generally weaker than those of the Hellenistic eastern provinces, Roman law spread more rapidly and with greater permanence. However, this law was not imposed on the subject peoples by force. On the contrary, the laws and customs of non-Roman communities generally operated intact except insofar as they might prove embarrassing to Roman rule. In a sense, Roman law evolved as the sole law of the Roman world when all the free inhabitants in the empire were granted Roman citizenship by the constitutio Antoniniana of Emperor Caracalla in AD 212 – but only in a sense. In reality, local systems of law did not disappear but remained applicable mainly in the form of custom. These systems adapted and influenced Roman law in diverse ways. Thus, the law operating in the provinces existed as a blend of Roman law and local practice. It varied in areas and was remote from the refinement and sophistication of the classical system. The process that has been labelled ‘vulgarization’ of Roman law emerged in this period and it was greatly advanced when the Principate age came to an end.

The decline of the comitial legislation

Augustus, intent on exercising his powers within the framework of the republican institutions, refrained from assuming the right to legislate alone. Instead, he abided by a tradition that accepted comitial enactment as the exclusive source of legislation. Thus, he used the assemblies to procure the enactment of the legislative measures that appealed to him. Some measures were passed directly on his motion and are hence called leges Iuliae.1 Others were passed on the motion of consuls or praetors, though obviously he was their real promoter. In this way, important statutes were passed concerning legal procedure (leges Iuliae iudiciorum publicorum et privatorum);2 marriage and divorce (lex Iulia de maritandis ordinibus, lex Papia Poppaea);3 adultery (lex Iulia de adulteriis coercendis);4 the repression of electoral corruption (lex Iulia de ambitu);5 and the operation of the senate (lex Iulia de senatu habendo).6 Other noteworthy legislative enactments of this period were the lex Fufia Caninia (2 BC) and the lex Aelia Sentia (AD 4) that introduced restrictions on testamentary manumission; and the lex Claudia, a law passed under Emperor Claudius, that abolished the guardianship of the nearest relatives (tutela legitima)over women.7

Almost since the emergence of the new order, comitial legislation was destined to wither away. It yielded to the necessities of a community transformed from a city-state into a world empire, and a political system where the leadership shifted from short-term magistracies to the supremacy of a single ruler. The substance of legislation had become too complicated to be entrusted to a metropolitan electorate renowned for volatility and generally ill-informed. Thus, after the reign of Claudius (AD 41–54) few legislative measures were passed through assemblies, and comitial legislation had entirely disappeared by the end of the first century AD.8

However, even as popular legislation was becoming obsolete the popular participation in public affairs was sustained as a constitutional fiction for the legalization and legitimation of the emperor’s power. The republican idea of the sovereign people as the ultimate legitimation of political power was so strongly entrenched by tradition that a formal lex, as an act of popular endorsement, had to be passed to invest the princeps-emperor with supreme powers. Thus, the practice emerged whereby the senate passed a resolution on the accession of a new emperor that recommended the conferment on him of the tribunicia potestas and those supplementary powers recognized as attributes of the imperial office. It also embraced the routine event where the people enacted the terms of this resolution in the form of a statute, commonly described by the old name lex de imperio.9 Throughout the Principate, the legal basis of the emperor’s position still derived from the grant of the republican proconsular and tribunician powers that Augustus originally acquired from the senate and the people. After comitial legislation in general had disappeared, this grant was regularly renewed by the senate, the successor of the assemblies’ full legislative powers, on behalf of the populus Romanus upon the accession of the next holder of the imperial office.

The magisterial law

During the long period after the enactment of the Law of the Twelve Tables, an intricate legal system developed from the interaction between custom, enacted law and case law. It embodied different layers of legal norms that coexisted and were mutually influential. The Roman ius civile formed the earliest layer with its basis in statutory law and customary law as we have observed. From the middle of the third century BC, a second layer emerged: the ius honorarium or magisterial law created by the praetors and other magistrates charged with the administration of justice. This body of law originated from decided cases and its essence was common sense, expediency and fairness. During the later republican period, its practical importance surpassed customary and statutory law.

After the establishment of the Principate, Roman law still comprised the ius civile and the ius honorarium: the original core of the civil law and the law derived from the edicts of the jurisdictional magistrates (especially the praetors). However, since the inception of this period the productive strength of the magisterial edict started to weaken. As praetorian initiatives became increasingly rare, the ius honorarium gradually became fixed in form and nearly as crystallized and immutable as statutory law. The changes in the edicts forged by the magistrates largely pertained to measures introduced by other law-making agencies (for example, senatus consulta). Finally, pursuant to Emperor Hadrian’s orders in the early second century AD, the permanent edict of the praetors and the aediles was recast, unified and updated by the jurist Lucius Salvius Iulianus (probably during the latter’s praetorship). The codified edict was ratified by a senatus consultum in AD 130 and thereafter magistrates were bound to administer justice in individual cases exclusively on the basis of the reformulated edict.10 Although edicts were still annually issued by magistrates, the latter had no control over their content. For all practical purposes, the edictum perpetuum thus evolved as established law; any further necessary changes had to be initiated by imperial enactment.

The codification of the edict marks the end of the ius honorarium as a distinct source of law. Thereafter, the imperial instruments of law-making attended to the further development of Roman law in a similar manner as in earlier times the edicts of the jurisdictional magistrates had refined and enlarged the original body of the civil law. However, the distinction between ius civile and ius honorarium persevered as long as the judicial system allied to these bodies of law still operated, and the Roman jurists could further develop these bodies by creative interpretation of the legal rules and institutions they embodied. Over time, new forms of dispensing justice superseded the traditional republican system of legal procedure as the sociopolitical environment changed. As a result, the distinction between the two bodies of law, having become one of form rather than substance, was obliterated. The fusion of ius civile and ius honorarium was also precipitated by the Roman jurists who, by developing both masses of law in common, gradually removed their boundaries. In the later imperial era the resultant combination of these two sources of law was designated ius, in contradistinction to the body of rules derived from imperial legislation known as lex.

Legislation by the senate

As we have observed, the senate in the republican era theoretically had no direct legislative powers. Its decrees (senatus consulta) were merely resolutions of advice to the magistrates and had no legal effect unless they were incorporated into a statute or a magisterial edict. However, in the later part of the republican period the senate exercised a very strong law-making influence through its ever-increasing involvement in the legislative process. Ordinarily, before legislative proposals were submitted to the people for approval the drafts were thoroughly discussed in the senate and any necessary amendments were executed in accordance with the views of the majority of senators. The final formulated draft would be incorporated in a senatus consultum advising the magistrate concerned to submit it to the people. Thus, the subsequent enactment of the proposed measure by the assembly virtually amounted to nothing more than a formal ratification by the people of the senatus consultum’s terms. Moreover, the senate increasingly assumed the task of guiding the praetors and other jurisdictional magistrates in the issuing of their edicts. In this way, the senate notably contributed to the creation of fresh ius honorarium: the law that derived its formal force from the imperium of a magistrate, as opposed to the ius civile that existed as the law extracting its formal force from statute or custom. The last years of the Republic featured the occasional event where a measure proposed by a magistrate that had the senate’s sanction was not submitted to the people but immediately came into effect. A rationale is that the popular assemblies were now quite unrepresentative and demoralized, and thus could no longer serve as effective organs of government.

In the first decades of the Principate, the role of the senate in the law-making process was more pronounced as legislation by the assemblies faded. Although comitial and senatorial legislation apparently coexisted for a period, the senate progressively assumed the position of the state’s regular legislative organ. In time, the senatus consultum rather than the lex became the chief means of legislation. Resembling the pattern followed under the Republic, the senatus consulta were couched in the form of instructions addressed to magistrates and were assigned the name of the magistrate who proposed them rather than the reigning emperor. As elaborated in Chapter 7, in the early imperial period the senate still retained the tradition of existing as a privileged order but was actually composed of the emperor’s nominees. From the start, the senate was virtually a tool of the emperor and had no free hand in the matter of legislation any more than it had in other matters. Indeed, most senatorial decrees were passed on the initiative of the emperor or at least with his acquiescence. The tribunician power was a characteristic element of the imperial office that could be wielded by the emperor to impede any act of the senate at any time. Therefore, we may surmise that during the Principate a senatus consultum was an ordinance that essentially engaged the authority of the emperor. Given this situation, it is easy to fathom that magistrates had to implement it precisely as if it were a statute, even though in terms of form the relevant instruction still committed its execution merely to their discretion. The fact that the senatus consultum was practically treated in much the same way as a statute rendered it a vehicle of legislation, although it appears unlikely that any specific constitutional action emerged to equate the resolutions of the senate with the leges.

In the first two centuries of the Principate, numerous senatus consulta were issued that effectuated important changes in the areas of both public and private law. An early senatorial decree of this period was the senatus consultum Silanianum of AD 10 that aspired to repress the frequent killing of masters by their slaves.11 Other important senatorial resolutions of this period embraced: the senatus consultum Vellaeanum (AD 46) that forbade women from assuming liability for debts of others, including those of their husbands;12 the senatus consultum Libonianum (AD 16) that imposed the penalties of the lex Cornelia de falsis for the forging of testaments;13 the senatus consultum Trebellianum (c. AD 56) and the senatus consultum Pegasianum (AD 73) that concerned the acceptance of inheritances subject to fideicommissa;14 the senatus consultum Iuventianum (AD 129) that addressed matters such as claims of the Roman public treasury (aerarium populi Romani) against private individuals for the recovery of vacant inheritances;15 the senatus consultum Macedonianum (second half of the first century AD) that prohibited loans to sons who remained subject to patria potestas;16 and the senatus consultum Tertullianum, passed in the time of Hadrian, that granted mothers the legal right of succession to their children’s inheritance.17

In the course of time, as the senate degenerated into a servile instrument of the emperor, its authority as an autonomous organ of legislation diminished and its resolutions increasingly became little more than mere declarations of the emperor’s will. Since the era of Emperor Claudius, senatorial resolutions were usually drafted by imperial officials and the relevant proposal was recited in the senate by either the emperor or, more often, an official acting in his name (oratio principis). The senators were then invited to express their views and a vote was conducted. However, the emperor’s influence on the senate entailed the latter never failing to agree with the main premises of the proposal.18 As the movement towards absolute monarchy advanced, the terms of the emperor’s proposal were increasingly adopted as a matter of course by the senate without even the pretence of a discussion. By the end of the second century AD, this practice had become so routine that it was customary to label a senatus consultum as an oratio of the emperor on whose initiative the senatus consultum was passed.19 The result was that, in the same way as legislation by the senate had superseded comitial legislation, imperial legislation gradually replaced senatorial legislation, which eventually vanished in the third century AD.

Imperial law-making

Augustus exhibited deference to the old republican institutions he claimed to have restored by consistently refusing to accept direct law-making powers that could supplant those of the established organs of legislation. So long as the principles of the Augustan constitution retained their vitality, the emperor achieved his legislative goals indirectly by regularly using the popular assemblies and then the senate. However, the emperor not only controlled legislation but, since the start of the Principate period, had diverse methods for creating new legal norms directly without appearing to legislate. The emperor’s law-making authority was initially based on his magisterial powers, especially the imperium proconsulare maius, and his tribunician potestas. As the imperial power increased over time at the expense of the old republican institutions, the enactments of the emperors (consitutiones principum) were recognized as possessing full statutory force (legis vigorem) and functioning as a direct source of law alongside the leges and the senatus consulta.

The second century jurist Gaius enumerated imperial constitutions along with other sources of law and declared: ‘A constitution of a princeps is what the emperor has authorized by decree, edict or letter. Nor is it ever doubted that this has the force of law, since the emperor himself receives his imperium by a law.’20 In other words, the law that conferred imperium on the princeps-emperor (lex de imperio) transferred to him the authority to legislate in the name of the Roman people. When this quoted passage is considered in light of the actual legal situation in Gaius’ era, it implies nothing less than whatever the emperor decreed as the law possessed the validity of a formal statute (lex), i.e. a statute like those which in the republican period were formally enacted by a popular assembly authorized by the senate. The foundation of the imperial legislative authority is not discovered in legal rationales but in political reality: the emperor’s power evolved so that his assumption of a direct legislative role could not be challenged. Indeed, the growth of imperial legislative authority was seemingly gradual. The imperial office in the late Principate period operated as the ultimate source of all administrative, legislative and judicial activity. It did not resemble the same office as that established by Augustus. It displayed a far more autocratic nature and assumed many characteristics of a monarchy.

Four types of imperial constitutions are commonly recognized: edicta, rescripta, mandata and decreta.


As elaborated previously, under the republican constitution the higher magistrates of the Roman state had the power to issue edicts or general proclamations that enumerated their orders or the policies they intended to observe in matters falling within their respective spheres of competency (ius edicendi). As holder of the magisterial imperium, the princeps-emperor also possessed this power. But as the emperor outranked all other magistrates in authority and his sphere of competence was virtually unlimited, his edicts were much broader in scope than those of the regular magistrates. These edicts addressed the entire business of the state and operated during and even after the reign of the emperor who issued them, unless they were repealed expressly or implicitly.21 The scope of imperial edicts encompassed such divergent matters as private law, criminal law and procedure, the constitution of the courts, the organization and administration of the provinces, and the bestowal of the Roman citizenship.22 The category of imperial edicts incorporated, for example, the constitutio Antoniniana (AD 212), whereby Emperor Caracalla granted the Roman citizenship to all the free inhabitants of the empire.23


The term rescriptum denoted the emperor’s answer to a petition or inquiry. Such petitions and answers might relate to all sorts of matters, but the present context focuses on those that invoked and resolved questions of law. A distinction was delineated between two types of imperial rescripts: epistulae and subscriptiones. The former were embodied in a separate document and were addressed to state officials in Rome or in the Provinces.24 The latter were responses to petitions from private citizens written on the margin or at the end of the application itself.25 Rescripts were particularly important for the development of the private law in the second century AD, when it became customary for judges and private citizens to petition the emperors for decisions on difficult questions of law. Initially, the imperial opinion was deemed to have only an advisory character but it eventually acquired the same force as a general rule. When an imperial rescript settled a point of law invoked by the facts stated in a petition, any judge acting under the emperor’s authority would naturally accept the latter’s determination as binding if the statement of facts was validated as accurate.26 Furthermore, the emperor’s ruling on a point of law contained in a rescript was treated in practice as a binding statement of law for all future cases. In this way, a new body of legal rules developed that had assumed voluminous proportions by the end of the second century AD.27 Jurists of this period formed private collections of imperial rescripts, large parts of which come down to us through the codification of Justinian and other post-classical compilations of law.


The mandata were the emperor’s administrative instructions to officials in his service that pertained to the conduct and execution of their official duties. As evidenced by the fragments preserved in later compilations of law, the most important mandata were addressed to provincial governors and concerned provincial administration (especially its financial side), while others dealt with private and criminal law and the administration of justice.28

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