The aim of the “European Convention for the Protection of Human Rights and Fundamental Freedoms” is to establish a protection system which ends the monopoly of the States on human rights by transferring them into the competence of supranational organizations. Thus, the Convention, unlike other traditional international treaties, provides a common system of guarantee by means of a well-established control mechanism. On the basis of the case law arising from such a mechanism, the European Court of Human Rights has strongly stated that the Convention is “a constitutional instrument of European public order” in the case of Loizidou v. Turkey on 23 March 1995. By using the term “constitutional”, the Court refers to the effectiveness of the fundamental rules to which the contracting States are subject, whereas it does not define the concept of “European public order”. Even before the above-mentioned decision of the Court, some authors, in order to emphasize the difference of the Convention to other international agreements and human rights documents, have already qualified it as a legal text of which the aim is to establish the “public order of liberal democracies”. In the administrative law, the concept of European public order is an important instrument providing the judge of the criteria to be used in concretizing the public order. The Article 90 of the 1982 Constitution amended in 2004, has ended the debate regarding the application of the European public order in the system of the hierarchy of norms. The judge shall apply the provisions of the Convention according to that Article stating that “in the case of a conflict between international agreements in the area of fundamental rights and freedoms duly put into effect and the domestic laws due to differences in provisions on the same matter, the provisions of international agreements shall prevail”. Keywords: European Convention for the Protection of Human Rights and Fundamental Freedoms, human rights, public order, administrative law, liberal democracy.