The chapter considers the principles of primacy and the direct effect of the EU provisions. The doctrine of direct effect can only really be understood against the background of another principle of EU law: the principle of primacy (or supremacy). The chapter presents long-standing and continuous case-law of the Supreme Court in respect of ensuring that EU law provisions precede before conflicting national provisions and ensuring full effect to directly effective EU law provisions. The chapter covers such issues as the reception of the principles of primacy and direct effect by the Supreme Court, the functions of these principles in adjudicating practice, and their consequences for the judgments and other judicial decisions.