The development of private military companies goes beyond the perception and definition of the traditional mercenary activity. The outsourcing of certain tasks that traditionally belong to royalty is an acknowledged fact in the United States, as in Great Britain and South Africa. Those private military companies’ expansion responds to the multiple challenges of international security : lack of recruiting, media impact of military losses, reluctance to commit to conflicts without strategic interest. Indeed, these countries have implemented a more or less rigorous legal framework to control the activity of this expanding sector. In spite of the apparent contradiction between these companies’ inherent pursuit of profit and the notion of public service that presides over national armies, the authors of this article consider that these entities are bound to complement each other and call for the definition of a legal framework in France in which private military companies may fit and develop.