Information sharing has occurred over the years within the AFSJ in the absence of a comprehensive data protection framework; and on the basis of informal agreements between legally and structurally different bodies, equipped with different tasks, often in contrast with the legality principle. This paper investigates whether today, in the design of law enforcement modalities of access to immigration of databases, data protection could trigger the (at least partial) formalisation of informal interoperable networks. The research would thus test to what extent a stronger compliance of interoperability mech-anisms with the legality principle fosters a renewed constitutionalisation of information sharing poli-cies within the AFSJ.