Historians today discuss the rules and regulations followed by medieval church courts by focusing on the development of so-called “Romano-canonical” procedure during the formative period of Roman and canon law from the time of Gratian (around 1140) to the completion, in the 1270s, of the most successful handbook on the subject, the Speculum iudiciale of William Durand. The guidelines laid down in the Speculum summarize more than a century of systematic effort at the schools of Bologna and elsewhere to strike a balance between, on the one hand, the obligation of judges to investigate the facts of a case unilaterally and, on the other, the right of defendants and adversaries to a fair trial. The specifics worked out by contemporaries have fascinated modern observers, not least for their innovative features. In twelfth- and thirteenth-century jurisprudence, demands of due process, the double jeopardy clause, presumption of innocence, and other fundamental standards of justice in the West found their first coherent expression. Simultaneously, though, research has operated under the erroneous assumption that manuals like the Speculum iudiciale were meant to cover the whole range of mechanisms shaping ecclesiastical adjudication.