This paper addresses one of the major legal issues concerning the debate about the legal value of the Universal Declaration of Human Rights (UDHR): Is the UDHR cogens? The authors explain legal problems related to the concept of cogens in order to show that the Universal Declaration cannot be classified as an imperative rule of law, even though some of the prohibitions that are implied in the UDHR have this nature. The authors present the dangers of the trivialization of the concept of cogens and the importance of preserving its essence as a rule that does not support repeal of any kind and under any circumstances. This paper searches to reject all the interpretations that would unduly expand the content of the concept of cogens, which is contained in article 53 of the Vienna Convention.