I could not have written the following 20 years ago, when the number of books on the modern private military and security contracting sector could be counted on one's fingers with digits left over, but there are now so many books that it constitutes a veritable library; some much better than others.
The latest entry is by Laura Dickinson, a law professor at Arizona State University who has been writing on the legal aspects of contracting for years. Happily, her book is one of those that is clearly better than others.
Professor Dickinson's focus is on the legal and public policy reforms that might increase accountability of private military contractors (PMC). By accountability she also explicitly includes the public values of human dignity, public participation, and transparency
One of her first points, which seems at first arguable given the now voluminous legal literature on private military contractors, is that international law scholars have not addressed outsourcing in a comprehensive way. By that she means that while scholars have applied international legal norms to non-state actors in general the category is too broad because a private contractor is far different from a guerrilla soldier.
http://www.atimes.com/atimes/Middle_East/MC26Ak02.html