The problematic character of a principle of investigation, surveillance and control entrenched in the heart of the state is nowadays widely recognized. The reason is that it has been formerly constituted as a public problem. This process can be precisely dated: it is a fact of the 1970s, when came about an authentic politization of the set of phenomena described as “social control.” The article proposes an exploratory analysis of this process through the question of data protection. The comparison between France and Germany makes it possible to show that if in these two countries, as in most liberal democracies, a similar process retrospectively appears to have led to similar results, it is not the less true that a specific path proves in each case to correspond to a singular test.