General principles of European Union law are unwritten legal rules whose purpose is to fill the gaps and are an aid in the interpretation of law and are among the primary sources of European Union law. Those general principles developed through the practice of the Court, and some have emerged from the constitutional traditions common to the Member States. The Court of Justice of the European Union (CJEU) has recognized a large number of general principles of EU law and is therefore obliged to protect them. One of the most important principles is the Charter of Fundamental Human Rights of the European Union which is guaranteed by the European Convention on Human Rights and Fundamental Freedoms. Through the individual cases, which have been elaborated in this paper, it can be seen how the Court of Justice has confirmed a principle as part of the general principles of EU law and how that principle is protected.