This article examines the ‘full jurisdiction’ requirement under Article 6 European Convention on Human Rights (ECHR) and its implementation within European Court of Human Rights (ECtHR) case law. It first analyses the theoretical foundations for ‘full jurisdiction’ which implies, in principle, a substitutive review of the merits of administrative decisions. [---] This article suggests that the ambivalence and inconsistencies within ECtHR case law can be explained in terms of the principle of separation of powers, which still underpins most legal systems of signatory states to the ECHR.