One of the most important issues in the law of international custom is the definition ofthe forms of acceptance of general practice as a legal norm (opinio juris). The lack ofconsensus on this issue at the international level and the common position in scienceresults in the poor effectiveness of the legal regulation of inter-state relations. Researchwork often uses non-objective approaches. The present article contains separatebut important theoretical provisions and proposals to address this problem. Thus,the existence of opinio juris is an inherent subjective element of the customary rule ofinternational law, as is the existence of practices that satisfy the necessary requirementsof customary rule formation. Only states and other subjects of international lawparticipating in international norm formation process can be recognized as subjects ofrecognition. Such actions may be manifested in the actions of state authorities and theirofficials, who may act on their behalf in accordance with international law and/or the lawof States. Opinio juris from the part of states is generally implemented in the course ofgeneral practice. Recognition must be exercised by legal means and be legitimate underthe law of the state and its international obligations. Among the main forms of recognition,together with acquiescence, are: a unilateral statement by the head of state (government),another state-authorized official, the head of the international intergovernmentalOrganization, other subject of international law; the inclusion of a rule of conduct in adomestic legal instrument; the inclusion of a rule of conduct in an international treatyor other based on it, a legally binding international legal act adopted by its parties inview of these documents as acts of unilateral recognition; under certain conditions, ajudicial decision in a state. The basic condition of the universal acceptance of the ruleof international law is its acceptance by the majority of states (established by the worldcommunity) whose interests are most affected by the application of this rule. This requiressome legal formalization, the codification of qualitative and quantitative criteria and thecorresponding indicators of the formation of the customary rule of international law. Theelaboration and adoption of a convention on the law of international customs would helpto reconcile the differences in the positions of subjects of international law and develop aunified approach in that regard.