JOSEF MRÁZEK CYIL 7 ȍ2016Ȏ practice of states is not by itself sufficient to create customary international law. The legal position ( opinio iuris ) of states is of fundamental importance. In international law it is necessary to distinguish political, moral and legal phenomena. This means to differentiate “legality” and “legitimacy”. Besides, customary rules on the use of force cannot be interpreted out of the UN Charter principles. A right to any military (humanitarian) intervention was not embodied either in the UN Charter or in modern general international law. Humanitarian intervention involving the threat or use of armed force and undertaken without authorization of the UNSC will, as a matter of principle, remain in breach of international law. 46 In Simma’s words, such a general statement cannot be the last word. He maintains that in any instance of humanitarian intervention a careful assessment will have to be made of how heavily such illegality weighs against all the circumstances of a particular concrete case. 47 Controversies about prohibiting the use of armed force have focused mostly on self-defence or a right to military (mainly humanitarian) intervention. The extensive and restrictive approach to prohibition (customary) of the use of force in international law, are discussed. 48 According to the extensive approach, it should be inconceivable to remain limited to the text of Art. 2 (4) or of Art. 51. Each use of force must then find its “legitimacy” relying on particular events and “necessity” of action. O. Corten is in favour of a “restrictive approach” to customary prohibition of the use of force, consisting in adherence to Art. 2(4) and Art. 51 of the UN Charter. Nevertheless, he recognizes, that “the right to humanitarian intervention is acceptable in the light of the progress of the humanistic values at the heart of international community.” He seems to believe that it is objectively necessary to allow certain unilateral actions in cases in which the collective security mechanisms have not functioned. 49 Some international law lawyers presume that regional enforcement actions do not require in advance an explicit authorization by the UNSC. It was also asserted that the text of Art. 53 (1) is not “unambiguous”. 50 Art. 51 is the legal foundation of the NATO Treaty. This Alliance is not a regional organization in the sense of Chapter VIII of the UN Charter. In legal terms NATO may be authorized by the UNSC to use armed force. Any unilateral offensive self-help by threat or use of armed force without a basis in Chapter VII would be in discrepancy with the UN Charter and ius cogens norms. Failure of the UNSC to disapprove of a regional military action could not be considered as “tacit” or “implicit” authorization. An opinion that Art. 53 (1) does in good faith leave room for the possibility of implicit as well as ex post facto authorization is a subject of controversy ostensibly enabling a dangerous 46 Supra note 2, p. 6. 47 Ibid ., p. 6. 48 Supra note 45, pp. 802-822.