11 Enforcing EU law – direct actions
Having a system of rules in place is one matter. Ensuring those rules are enforced is an entirely separate issue. The primary responsibility for bringing actions for enforcement of EU law lies with the Commission under Article 258 TFEU. This empowers the Commission to bring infringement proceedings against a member state allegedly breaching its obligations under EU law. As part of the procedure states are giving the opportunity to submit observations before the Commission then delivers an opinion. A member state that fails to comply with the resulting judgment is fined and the fine is on a daily basis. A good example case to look at is Commission of the European Communities v Greece (Case C-387/97)  ECR I-05047.
It is not just the commission, member states also have the right to bring actions against each other under Article 259 TFEU, but this is rare.
Also, the vast majority of actions in which individuals (that is, natural persons and legal persons) rely on rights derived from EU law are commenced in the national court.