Monitoring of the work of all institutions, bodies, offices and agencies is performed by the Court of the European Union, whose activity is the main topic of this work. However, in order to make it clearer how he implements this control, it is important to familiarize yourself with some basic principles and rules according to which the European Union functions. For this reason, I will introduce the internal functioning and the most basic tasks of each institution of the European Union, we will see on which principles and according to which rules the work within the institutions takes place. It will also be possible to see that the European Union has its own "administration" which enables it to function normally and on time. Every institution has some form of administrative apparatus that is organized within it so that they can focus on the main tasks for which they exist. Although the European Union is a complex international organization that functions similarly to the member states, its activities are interwoven between different bodies, which is why judicial control carried out by the Court is extremely necessary. As an institution, it has existed since the very beginning of the European Union, and its powers have expanded with each extension of the treaty. I believe that it is one of the most important institutions because it ensures the correct application of the entire law of the European Union. From his many powers, he shows that it is among the most important that the law of the Union is applied uniformly and correctly throughout the territory of the European Union. It has several basic functions and responsibilities that I will deal with in the following text in order to point out its importance. In addition to him, on this important task, other institutions such as the European Ombudsman and the Data Protection Supervisor are also active. All of them work according to one task, which is that the law of the European Union is applied as it is written in the Treaties and that there is no double interpretation. They are at the service of all states and even individuals so that the Union can function as it was initially conceived.