Abstract: This article reviews the new international criminal justice agencies jointly falling under the term “international mechanisms”: International Residual Mechanism for Criminal Tribunals, Residual Mechanism of Special Court for Sierra Leone, International Investigative Mechanism for Syria, and International Investigative Mechanism for Myanmar. Analysis is conducted on the legal nature of these institutions, primarily from the legal grounds of their establishment, competence, and some aspects of activity. Particular attention is paid to the legal position of the Russian Federation with regards to the indicated agencies. The research is carried out on the basis of analysis of constitutional documents of international mechanisms, resolutions of international organizations within the framework of which are created the corresponding institutions of international justice. The following conclusions were made: all “mechanisms” that are currently in force within international justice experience the deficit of legitimacy: methods and circumstances of their formation to one or another degree do not align with the existing norms of international law; there is a tendency to go beyond its scope of competence; the concept of the indicated mechanisms consists in the activity, which in essence represents a judicial and/or investigative activity implemented in both, “preceding” and “residual” forms. All of the aforementioned peculiarities do not deprive the indicated agencies of their judicial and investigative nature.