The use of mercenaries has been historically a constant phenomenon till almost the end of the XX century, when their activities were criminalized by the international community. Parallel to that phenomenon European States, during their colonial expansion over all continents, authorized two other forms of similar violence by non state actors: the corsairs and the colonial merchant companies, such as the East India Company or the Hudson Bay Company. At the threshold of the XXI century we are witnessing a similar phenomenon. Although mercenaries have not completely disappeared "private military and security companies" (PMSC), in the course of the past 20 years, have increasingly taken over the traditional activities carried out by mercenaries before1. Contrary to mercenaries, private military and security companies are transnational corporations legally registered which obtain contracts from governments, private firms, intergovernmental and non governmental organizations. In low intensity armed conflicts or post conflict situations such as Afghanistan and Iraq their employees, contracted as civilians but armed as military personnel, operate in "grey zones" as unlawful combatants without oversight or accountability, under murky legal restraints2 and often with immunity. .
The outsourcing of a number of basic functions which traditionally were carried out by national armies or police forces, known as the top-down privatization, has blurred the borderlines between the public services of the State and the private commercial sector. The activities of humanitarian non-profitable organizations and those of military and security transnational companies working for pecuniary gain3 are also being blurred. Private military and security companies often provide security and protection to humanitarian non governmental organizations in conflict or post-conflict areas where it has become difficult for the population to distinguish one from another.
