Access to court has long been recognised as an essential element of a Union based on the rule of law. This book asks, how can Member States ensure that their rules on standing guarantee that right? The book answers this question by analysing the requirements of EU law from two angles: first, the effective protection of Union rights; second, the effectiveness of Union law per se. With detailed case law examination, the book formulates an autonomous Union law doctrine of standing based on the principle of effective judicial protection. It then goes further, setting out an effectiveness test of Member States' enforcement mechanisms, to ensure that EU law is rendered operative in practice. This is a rigorous study on a question of immense importance.