Having regard the fact that the legislative and executive rule makers in a legal system might not envisage rules for all issues in advance, and that even the existing rules require to be interpreted, general principles of law which are invoked by practitioners and justices for the interpretation of legal norms and filling legal gaps function as an important source of legal orders. Those principles have been used by the judiciary of the legal order from the very outset in the European Union (EU) law which is similar to both international and national legal systems in some ways. They have also functioned as a jurisprudential set of reference norms. This study deals with these principles from the EU law point of view. The role these principles have played in the EU legal order, especially with regard to the protection of human rights will also be dealt with.