It is well-established law in France since at least 1932 that a public authority cannot delegate to private bodies core public functions, such as security for example. The Constitutional Council recently reiterated such a prohibition against Parliament that wanted to pass a bill on videotaping. The bill authorized local government to delegate this function to private entities.
In its decision (Conseil constitutionnel, 10 mars 2011, Loi d’orientation et de programmation pour la performance de la sécurité intérieure, n° 2011-625 DC, available here), the Constitutional Council reiterated the prohibition, holding that:
«Whereas by authorizing any corporate body to put in work surveillance devices beyond the “immediate” accesses of its buildings and installations and by entrusting to private operators the responsibility to exploit systems of videotaping on the public highway and to view the images on behalf of public bodies, the disputed provisions make it possible to invest private individuals with missions of general surveillance of the public highway (“voie publique”); that each one of these provisions makes thus possible the delegation to a private individual of general administrative police powers inherent to the exercise of the “public powers” (“force publique”) necessary to the guarantee of rights; that, consequently, [this provision] must be declared contrary with the Constitution».
To understand fully this judgment one has to consider article 12 of the Declaration of human and civic rights of 26 august 1789 that provides: «To guarantee the Rights of Man and of the Citizen a public force is necessary; this force is therefore established for the benefit of all, and not for the particular use of those to whom it is entrusted». This public force cannot therefore be delegated to private entities.
This is just an application of old case-law. On 17 June 1932, in the case «Ville de Castelnaudary» (available here), the Conseil d’Etat held that:
«Whereas the deliberation quashed by the attacked decree ratifying a subscription made to the “Fédération audoise chasse-pêche-agriculture” for the use of one of the particular guards of this Federation for the intermittent monitoring of the rural properties; that the service of the rural police, by its nature, could be entrusted only to agents placed under the direct authority of the public administration; that by entrusting this service to a federation of private owners, the town council of Castelnaudary exceeded its powers».