One of the few scholars currently focusing on vinaya literature is Shayne Clarke. His Masters’ thesis is now available online:
Clarke, Shayne. Pārājika: the Myth of Permanent and Irrevocable Expulsion from the Buddhist Order: A Survey of the Śikṣādattaka in Early Monastic Buddhism. M.A. diss., University of Canterbury, 1999. (URI & abstract / PDF.)
Dr. Clarke and myself had the pleasure of meeting at the 2007 Hamburg Conference on the Ordination of Women, where his learned presentation stood out. (Incidentally, my report of this event became controversial enough to warrant a face-to-face meeting with one of the organizers; they have since put their own views into print. Update: Readers may also wish to consult the conference papers directly. [I trust that the participants gave their consent for online publication.])
If I may say so, Clarke’s thesis reads as an unusually accomplished piece of work for an M.A. (even in its slightly expurgated online form). His understanding of the vinaya as formulated in India is based, as it ought to be, on a survey of multiple nikāyas. In subsequent publications — see this list at his official site — Dr. Clarke effortlessly bins the received view of the Pali canon as the definitive record of the lives of Indian Buddhists.