The EU principle of mutual trust prescribes a broad-brush presumption of EU law compliance, quite problematic in light of the rule of law and effective judicial protection. The ECJ defines effective judicial review as the essence of the rule of law. But mutual trust precludes domestic courts from reviewing if courts of other Member States have actually complied with EU law, even if the breaches seem evident. The paper proposes that mutual trust should be conceived of only as a presumption that national courts comply with their own domestic law, given significant procedural, epistemological and cognitive limitations to domestic judges reviewing each other’s decisions relating to purely internal matters and domestic law. The paper argues that the same limitations should not prevent domestic courts and the ECJ – within the preliminary reference procedure – from reviewing if the EU law has been correctly applied by the issuing courts.