The lectures have four overarching themes, pursued in counterpoint. First, I argue that the civil law was not simply authored by a Republic bent on empire; it was itself inflected at every stage of development by its use in the governance of empire. That is so despite the ideological claim advanced by the Romans themselves, to the effect that Roman law and Roman courts were purely domestic in scope. Despite the regular reiteration of such claims, the Romans in fact regularly extended civil-law procedures to aid in resolving disputes among aliens.
Second, the civil law tradition owes the form and horizons of its historical self-consciousness to the moment when, in the late first century c.e. and beyond, jurists elaborated in argument upon just those mechanisms deployed in the language of statute to embrace alien categories of person and thing. Those same manoeuvres first visible in statute law – above all fiction and substitution – were taken up by jurisprudents to provide post eventum resolution to conflicts of law and to domesticate change in positive law as the empire embraced formerly alien subjects as citizens.
Third, despite Roman claims to the contrary, civil law forms of action are very much older than sacred or international law at Rome. Archaic civil law forms may thus be analysed to provide heuristic insight into the international law forms that the Romans largely invented on their basis. In an inverse and somewhat later transformation, the legal structures devised to explain the nature of magisterial power and to justify the exercise of power by Romans over others were both taken up to give normative justification to the surrender of power to and into the emperor. In this way, the abrogation of republican government was constituted as an act of republic constitutionalism, and the tradition of republican law forever compromised through support of monarchic rule.
Fourth, Roman jurists were aware that historical change in their own culture, as well as the extension of the law to alien populations, strained the capacity of legal language to give normative description to the world it was being called upon to govern. The attempt within the jurisprudential tradition to come to grips with this fact, and to account for it in legal philosophy, ultimately produced a body of social theory – on the legitimacy of law, on the nature of social reality, on the relationship of social facts to legal ones, and on the nature of language itself – of remarkable sophistication.