It began its opinion by reaffirming the doctrine of direct effect, established in Van Gend en Loos v Nederlandse Administratie der Belastingen.Para.
[2]The ECJ additionally reiterated its claims of legal supremacy in Costa v ENEL, underscoring the precedence of EU law over national law.Para.
[2]The ECJ concluded by formulating a new principle, namely that national courts have an obligation to “set aside” all statutes conflicting with EU law.
[2]The “setting aside” principle described by the Simmenthal decision has come to be known as “disapplication.” Subsequent case-law has extended the mandate of disapplication to all bodies established under national law to enforce individuals’ EU rights, even when the exercise of such authority undermines local constitutional rules.
[3] Because Simmenthal granted the power of judicial review to all national courts and tribunals, its disapplication principle indirectly overturned parliamentary sovereignty in Great Britain, the Netherlands, and other countries whose judiciaries had previously lacked authority to curtail majoritarian parliaments.