In almost every conceivable sector of Europe's composite administration, information is gathered and passed on between different national authorities amongst themselves, or between national and EU ad-ministration. This is particularly true of Europe's Area of Freedom, Security and Justice, and of the interoperable information systems that it has put in place. The EU constitutional framing of the rela-tions between information-sharing authorities is, however, less clear. The paper first takes an empirical approach. It maps existing practices of recipient authorities from a cross-sectoral perspective, but with a particular emphasis on the AFSJ. The second component of the paper is normative in nature, as it explores whether the EU's constitutional principles have anything to say on the duty of authorities to trust, or to double-check, the information they receive.