In the late Roman Empire, complexity and uncertainty created demand for responsa from the apostolic see. After the eleventh-century papal turn, new legislation and a different society generated new complexities and uncertainties. Decretals were not the only way to resolve them, but given the prominence of the tradition launched by Siricius and Innocent I, they were an obvious way. An unbroken chain of communication links the first and second decretal ages. Late Antiquity and the central Middle Ages need not be kept in separate compartments.

The first and second decretal waves, c. 400 and c. 1200, both responded to unresolved complexities arising from the evolution of separate social systems. In the standard gloss on Gratian, ‘Gloss II’, decretals from the two ages are brought into conjunction. Innocent I’s ruling about pagan marriages was generating thoughtful discussion eight centuries after his death. The standard gloss discusses it together with a decretal of Innocent III. Between Innocent I and Innocent III, the ‘Pauline Privilege’ system emerges clearly into view, taken for granted by Innocent III after an evolution at which for want of evidence we can only guess. How to integrate the earlier Innocent’s ruling with the ‘Pauline Privilege’ system? This is an example of how the horizon of reflection about a text can be enlarged over time, without losing contact with the original meaning, as it is applied in new context and to complex scenarios not originally envisaged.

With both the role of professionalization in the second decretal age, and the divergence between canon law and theology, contingency must be given its due, as against an assumption that the separation of theology from a canon law which was professionalized and based on papal decretals was in any way inevitable. Decretals and professionalization were indeed integrated in Western Europe around 1200, and in a different intellectual sphere from university theology, but there was no necessity about it. Without the legacy of the first decretal age, there might never have been a second decretal age, though there would surely have been a system run by academically trained lawyers. Similarly, there was no necessity about the separation of canon law from theology. A change of theological fashion is part of the explanation, but so too is the direction in which the Breviarium of Bernard of Pavia pointed the system. Bernard was the Dionysius Exiguus of his age.

The century between c. 1130 and 1234 was a time of great renewal and transformation in canon law when much of the foundation was laid that would define the legal structure of not only the church but also secular society well into modern times (see Chapter 30). At this time, papal legislation found its stride, in the form of papal decretals and conciliar decrees (notably from the four Lateran councils, 1123–1215). The inhabitants of Europe sought out the pope’s judicial decisions in unprecedented masses, creating a rich body of papal case law. At the same time, legal study grew exponentially at the law schools, particularly in Bologna, where an expanding and often innovative tradition of analysis and commentary, which were also inspired by the recently rediscovered Roman law of the emperor Justinian, brought canon law to new levels of complexity, sophistication, and precision.