Thomas J. McSweeney, William & Mary Law School, has published Magna Carta, Civil Law, and Canon Law in Magna Carta and the Rule of Law (Daniel Magraw et al., eds.; 2014). Here is the abstract.
With the 800th anniversary of Magna Carta approaching, interest has been piqued in the charter, which influenced the development of the common law in its early stages. One debate surrounding the charter is the degree to which Roman and canon law influenced the text. This debate has important implications for the identity of the common law. We tend to think of common law as an English institution, very different from those continental civil-law systems that trace their ancestry back to medieval Roman and canon law. If Roman and canon law influenced the charter, it could serve as evidence that the early common law was not so insular in its outlook as we have thought, and that it really should be placed in a broader European context.Download the essay from SSRN at the link.
Roman and canon law — collectively called the ius commune in the Middle Ages — certainly made their mark on Magna Carta, but this paper argues that the elements of the ius commune that found their way into Magna Carta were inserted not to influence the early development of the common law, as many scholars have assumed, but rather because ius commune, and more particularly canon law, was a political language that appealed to various important constituencies in England and abroad. Appeals to canon law in Magna Carta were more likely placed there to elicit support from the papacy than to reform English law. This paper places Magna Carta in the longer context of the Church reform movement and its instantiation in England — the Becket dispute — and argues that Magna Carta’s ius commune-influenced provisions were attempts by English actors to give universal significance to their local disputes.