It is only now I have started reading histories of Carolingian canon law in a systematic way that I have realised the peculiar position that many authors take on the legal position of early canons. Very often these are treated as legally binding, in the same way that canon law later was. If an early church council says that a matter is to be dealt with in a particular way, it is assumed that that becomes law and the whole church simply abides by this.
An alternative, which is almost equally unsatisfactory, is the assumption by some authors (such as Sylvia Konecny) that the impact of church law depends purely on political factors. Whether a royal divorce happened (as in the case of Charlemagne and Desiderius daughter) or didnt (as in the case of Lothar II) had nothing to do with church law and everything to do with the relatively political power of the two rulers.
All this suggests that scholars writing about early medieval church law need to start thinking about the questions that historians writing on early medieval secular law have grappled with for years: what does law actually mean, what is it intended to do and how is it used? Theres a whole debate that seems to have entirely passed modern canonists by, presumably because theyre working in a framework of Roman law (both late antique and eleventh century).
The first obvious point of similarity between the secular and ecclesiastical spheres is between law as aspiration versus law as application. The programmatic quality of Carolingian capitularies has been overstated, but there is a serious point being made. Many Carolingian laws are as much visions of what an ideal society should be like than strictly enforceable measures, and the same is true of many canons. I suspect that canonists have not taken this on board because they subconsciously feel that the symbolic use of law is a characteristic of primitive societies, which do not have a proper understanding of law. The example of the UK ban on hunting with dogs, however shows that symbolic laws are not restricted to legally unsophisticated societies.
Secondly, parallels with secular law may get us out of excessive hang-ups about enforcement of ecclesiastical law (or its lack). The characteristic of all state law-enforcement before the modern period (and specifically the development of police forces) is its reliance on occasional, exemplary punishment, as opposed to systematic repression of wrong-doing. It is likely too, that the canons had at least some deterrent power from the possibility that (in the reversal of the lottery slogan) it just might be you that got into trouble.
A final useful idea that comes from the study of early medieval secular law is that of customary norms (and hence law) as being negotiable rather than fixed. This has enabled studies of secular law in action to get beyond a simple dichotomy of laws as applied or ignored. Similarly, to see ecclesiastical cases as dealt with by negotiation between competing principles which were important but also malleable is more realistic than to attempt to fit a fixed legal framework around often specific and peculiar decisions.
What the study of the effects of early medieval canons offers to secular law, in return, is a way into the problem of why the powerful might obey the law, at least sometimes. Unlike with secular law, there was minimal direct coercive power behind the churchs demand for obedience to its norms; the Pope almost always had no divisions. (Nor, in practice, did Frankish rulers act to enforce such ecclesiastical demands, even if they might promise they would). And yet, for some of the Carolingian period, you can see powerful men adhering vaguely to some canonical principles (or justifying themselves by different canons when they did not). Lothar II did not simply repudiate his wife and dare the bishops to disapprove, and that was not purely because his political position was weaker than Charlemagnes, but also because Christian kingship/lordship was important to him.
The example of the Carolingian church and the (intermittent) conformity of kings and magnates to its demands and laws support the counter-intuitive suggestion that playing by the rules can sometimes be maintained within a system even without a strong authority enforcing such rules. Rulers and magnates gained prestige from behaving in accordance with church norms and (seemingly) lost prestige and social support by opposing the church (or particular churches). A triumph by law rather than simply force in a dispute brought validity to ones victory (for example, legitimacy to ones marriage). Theoretical support for the legal order was also sensible for anyone who feared being the underdog in a future dispute; law could be a source of protection as well as a restriction. Touch not the Lords anointed gave protection to Carolingian rulers even as it constrained their behaviour.
Yet what the Carolingian and post-Carolingian developments on marriage law, in particular, also suggest is that such a non-coercive system was difficult to maintain in the long run. If enough of the powerful refuse to acknowledge the rules in such a system (and a snowball effect is always likely), the rules effectively no longer exist, just as an unrefereed football match is always potentially likely to become a free-for-all. By the early eleventh century, as Georges Duby has shown, French rulers no longer cares about adhering to church rules on marriage. It is hard to argue that this was because Robert the Pious was in a stronger position with respect to the church than Carolingian rulers and so was more able to ignore their demands; it was more that adherence to church norms no longer seemed sufficiently advantageous. If applying insights about early medieval secular law can remind us that law does not have a fixed meaning throughout the centuries, studying early medieval canon law can reveal the extent to which almost all law in the early Middle Ages was essentially a confidence trick, a voluntary agreement by the powerful to accept small measures of legal constraint in their pursuit of power.