The Law Librarian Blog (LLB) has an interview with the Quid Pro Books publisher:
Excerpt “… Wait a minute, a law prof as independent law book publisher?! When I saw that Alan’s corrected and annotated version of Holmes’ The Common Law was available in eight digital formats and in paperback and read the Publisher Information page about Quid Pro, LLC, sidebar, right, my interest peaked. This isn’t some law prof who has gone the self-publication route because no major publisher would accept his 2010 edition of Holmes’ The Common Law. Quid Pro Books is a new venture that publishes eBooks of original manuscripts in law and law-and-society, in addition to classics, for worldwide distribution….” (Link to full LLB blog post and to Quid Pro Books.):
Other Sources of Information on law book publishers:
1) AALL CRIV List (not up to date, but still very useful)
2) Legal Researchers Desk Reference (from Infosourcing Publishing)