Various security-related clauses (such as public security or essential security interests) serve as exceptions from certain rules of EU law. For example, they may be invoked by the Member States when derogating from internal market freedoms or other EU rules. Also, there are bases for the EU institutions to invoke security exceptions, for instance when restricting access to documents according to Regulation 1049/2001, as well as certain procedural rights of parties (access to the file, duty to state reasons). Possibility to invoke such exceptions presupposes a certain level of trust towards the invoking authorities but does not exclude them from the scrutiny of the CJEU. The research aims to analyse its jurisprudence concerning the extent of leeway allowed by the Court to the authorities in such cases: what are the common patterns of scrutiny in different cases, has the extent of trust towards the authorities evolved in time, is it dependent on the Member State concerned, etc.