The main aim of this book is to argue that the use of private force by states has been restricted by a norm against mercenary use. The book traces the evolution of this norm, from mercenaries in medieval Europe through to private security companies in modern day Iraq...The norm against mercenaries has two components. First, mercenaries are considered to be immoral because they use force outside legitimate, authoritative control. Second, mercenaries are considered to be morally problematic because they fight wars for selfish, financial reasons...[refers to Executive Outcomes, Sandline]