However, the method of studying and teaching gradually developed: if the early decretalists made use of the elementary plan of the gloss and literal commentary, their successors in composing their treatises were more independent of the text; they commented on the titles, not on the chapters or the words; often they followed the titles or chapters only nominally and artificially.
In the sixteenth century they tried to apply, not to the official collections, but in their lectures on canon law the method and division of the "Institutes" of Justinian: persons, things, actions or procedure, crimes, and penalties (Institutes, I, ii, 12).
This plan, popularized by the "Institutiones juris canonici" of Lancellotti (1563), has been followed since by most of the canonist authors of "Institutiones" or manuals, though there has been considerable divergence in the subdivisions; most of the more extensive works, however, preserved the order of the "Decretals". In later times many textbooks, especially in Germany, began to adopt original plans.
In the sixteenth century too, the study of canon law was developed and improved like that of other sciences, by the critical spirit of the age: doubtful texts were rejected and the and tendency or intention of later laws traced back to the customs of former days.
In the eleventh century certain collections group under the same headings the canons that treat of the same matters; however, it is only in the middle of the twelfth century that we meet in the "Decretum" of Gratian the first really scientific treatise on canon law.
We administer Roman Catholic parishes and schools within the city of Detroit as well as Wayne, Oakland, Macomb, St. Raymund of Pennafort in the official collection of the "Decretals" of Gregory IX, promulgated in 1234 (see CORPUS JURIS CANONICI).These collections, which did not include the texts used by Gratian, grouped the materials into five books, each divided into "titles", and under each title the decretals or fragments of decretals were grouped in chronological order.Considered from the point of view of its expression, canon law may be divided into several branches, so closely allied, that the terms used to designate them are often employed almost indifferently: common law and special law; universal law and particular law; general law and singular law ().It is easy to point out the difference between them: the idea is that of a wider or a more limited scope; to be more precise, common law refers to things, universal law to territories, general law to persons; so regulations affecting only certain things, certain territories, certain classes of persons, being a restriction or an addition, constitute special, particular, or singular law, and even local or individual law.