For practitioners in the field, but also for academicians it is equally important to know that there exists, under certain circumstances, the possibility of bringing an action for annulment, having as object the legally binding EU acts. All questions concerning the action for annulment have their significance in the theory and practice of the field, but a consistent case-law is offered by the grounds for annulment, the plea of illegality and correlatively by the effects of the decision ruled within the action in for annulment, and these are some issues to which we shall refer further.