The article is devoted to the study of the correct application of the evaluative concepts contained in the norms of the Convention for the Protection of Human Rights and Fundamental Freedoms. Attention is drawn to certain difficulties in the application of the evaluative norms in the Convention: despite their objective necessity and usefulness, they create a room for the law enforcement entity’s own discretion up to subjectivism in resolving specific cases; they serve as an objective obstacle to the unification of the case law of the ECtHR and this creates preconditions for unequal implementation of ECtHR judgments in the national legal order; they cause the risk of errors in the application of the provisions of the Convention by the competent authorities of the Contracting States. It is established that the application of legal norms containing evaluative concepts is challenging not only owing to the specific properties of the evaluative concepts themselves, but also due to the peculiarities of adjudication by the ECtHR when applying the evaluative norms. The relevant case law of the ECtHR as well as examples of national legislation are analysed in support of these theoretical conclusions. Since the lack of uniform application of the evaluative norms of the Convention causes divergent use of the ECtHR’s judgments in the domestic judicial system, it is advised to follow a number of rules for reasoning of decisions by the domestic court. These rules will serve as a certain guarantee against ambiguous implementation of ECtHR judgments at the national level.