Are Security Council acts relevant to the formation of Customary International Law?

by Kristen Boon

Just like General Assembly resolutions can be indicative of state practice and opinio juris, I have always assumed that acts of the Security Council – an organ of the UN, composed of states – would be relevant as evidence and to the formation of customary international. Significantly, however, Security Council acts do not feature in the first report of the Special Rapporteur Sir Michael Wood, on the ILC’s current study on the formation of custom.  A word search reveals “zero” matches with Security Council, while the General Assembly comes up 13 times. There is no explanation in the report for why Security Council acts are not relevant to custom.

Given the Security Council’s power to legislate, this omission is both interesting and significant. One could surmise it is due to the Council’s composition – its members number 15 – as opposed to the universal membership of the General Assembly. Perhaps its not a big enough cross section, even though the P5 would presumably be big players in determining custom. Or perhaps it is related to the fact that the Council can act inconsistently, not always applying principles consistently in like cases. Further still, perhaps it emanates from distrust of the Council’s occasional role as a legislator. Indeed, if Security Council acts (and as a subsidiary matter, statements of Council members during meetings of the Security Council) are relevant to custom, then those same customary rules would bind the UN (and the Council as an organ of the UN), which raises important considerations with regards to the perennial debate about what legal limits apply to the Security Council.

The Council’s capacity to bind member states, and derivatively International Organizations, under Articles 25 and 48 is well established. Its ability to override inconsistent law under Article 103, and its demonstrated propensity to legislate in areas like anti-terrorism, and the many calls in the mid-2000s for Council power to be curbed through judicial review or other means, would lead one to expect at least consideration of the Council’s role.  It is noteworthy that in the Memorandum prepared by the Secretariat’s on the same topic, the Security Council is mentioned twice in relation to non-recognition of acts in breach of peremptory norms (citing the ILC’s commentary on State responsibility, which in turn cites Council resolutions on Iraq’s invasion of Kuwait and the situation in Rhodesia.) I note that Greg Fox and I are interested in the question of Security Council legislation, and are now embarking on an empirical assessment of the Council’s law-making in relation to the field of armed conflict.  As a result, I may have a vested interest in the debate…  Nonetheless, what do readers think:  should Security Council decisions be considered in regards to the formation of customary international law?

19 Responses

  1. I am one who thinks the UNSC’s authority is circumscribed by various rules of international law, only one of which is the Charter itself. I think the UNSC has acted ultra vires on a number of occasions. I published an article in the Georgetown JIL a couple of years ago on this topic:

    I would also agree with the choice of the ILC to not consider UNSC practice to have a disproportionate influence on the formation of CIL. The UNSC’s Charter powers have nothing to do with CIL formation.

  2. I don’t think Security Council resolutions have any unique affect on the formation of custom. But certainly the votes of the states making up the Security Council count as opinio juris. And isn’t the same true of the General Assembly? There is nothing magical about a UNGA Resolution, but unanimous ones effectively express the opinio juris of the entire international community.

  3. I think one answer to this very interesting question could perhaps lie, as the author of this post suggested, in the norms the UNSC can define, within its legal limits. For example, only the UNSC can qualify a threat to international peace and security, thus applying the Chapter VII, which previously lead to the setting-up of ad-hoc International Criminal Tribunals, among others…
    Anyway, thank you for bringing up this issue!

  4. Re: Just like General Assembly resolutions can be indicative of state practice and opinio juris, I have always assumed that acts of the Security Council – an organ of the UN, composed of states – would be relevant as evidence and to the formation of customary international.

    Me too. The Secretariat and Security Council have been publishing the yearly “Repertoire of the Practice of the Security Council” for decades now.

    It purports to provide comprehensive coverage of the Security Council’s interpretation and application of the United Nations Charter and its own Provisional Rules of Procedure. The whole undertaking is based on an explicit mandate contained in General Assembly resolution 686 (VII) “Ways and means for making the evidence of customary international law more readily available”.

    The Secretariat even provided annual reports on a retroactive basis back to 1946. If I recall correctly, the General Assembly staffed-out the studies of the basic proposal to the ILC through the Secretary General and the particulars, including Security Council reportage, were developed by the ILC. In any event the documentary history the development of the program is available from the ILC website

  5. Thank you for this interesting insight.
    It would seem that the UNSC’s influence on custom formation should be viewed from the custom-treaty paradigm. The UNSC’s authorities are ultimately treaty-based (particularly in Article 24 to the Charter). Additionally, in a sense, States have delegated their sovereign decision-making powers to the Council to act on their behalf.
    However, their decisions constitute a rather weak form of State practice and opinio juris. Though in Libya/Malta (¶27) the ICJ recognised that treaties (and hence also UNSC resolutions deriving from such treaties) are relevant to the development of custom, the indications for the development of custom are “primarily in the actual practice and opinio juris of States”. Moreover, it seems that there is a general approach in international law to regard the practice and opinio juris expressed by or through higher ranking State officials greater weight than other persons acting on behalf of a State in assessing a State’s approach to a potential norm. UNSC resolutions are at a relatively great distance from the higher ranking officials.

  6. There seems to be at least a fear that UNSCRs may contribute to CIL. UNSCRs on piracy off the coast of Somalia, in essence authorizing the piracy regime on the high seas to be applied to the territorial sea of Somalia, were explicit. This was in no way to be seen as contributing to CIL (e.g. UNSC Res 1846 (2008), op 11)): “and underscores in particular that this resolution shall not be considered as establishing customary international law;”

    More in general, I would say that UNSC practice is state practice regarding a treaty, capable of contributing to the formation of international law.

  7. Kirsten, here are a few brief comments: First, you seem to take as a premise that the Security Council has the power to legislate, but this is precisely controversial. There’s nothing in the Charter suggesting the existence of such a power, though some have argued that it falls within its wide powers to maintain or restore international peace and security. But moving from the idea that threats to the peace need to relate to concrete circumstances to an abstract notion that any act of (international) terrorism or proliferation of WMD constitutes such a threat simply serves to decontextualize determinations (and note that the Council did not actually ‘determine’ a threat to the peace in resolutions 1373 and 1540). As a result this move simply expands the concept of threats to the peace to include situations that are likely to endanger international peace and security, which are however subject to the province of Chapter VI and its provisions for the peaceful settlement of disputes.

    Second, note that the Court in Nicaragua stipulated that it was the attitude of States towards GA resolutions that one could deduce opinio juris from rather than the resolutions themselves (and even then, with all due caution, probably reflecting that the Declaration on Principles of International Law had been adopted by consensus and does not show the actual support by way of affirmative votes, and most likely also taking into account that conflicts over the existence or interpretation of certain rules had been papered over). Of course, in the advice on the Legality of Nuclear Weapons the Court adopted more broad language by saying that they may be evidence of customary international law or an emerging opinio juris. One may have doubts whether Council resolutions ought to be seen as contributing to State practice, since the Council itself cannot act and the exercise of its powers is not dependent upon a basis in international law more generally.
    Finally, Council resolutions may be analysed in the same manner as GA resolutions in terms of their contribution to opinio juris. In the Legality of Nuclear Weapons the Court referred to the circumstances of their adoption and their content. Basically one needs to establish the normative character of some of the content (in what manner are specific paragraphs formulated; do they use strong language or appeal to existing rules of international law); the voting pattern may be taken into account (unanimity), but this would appear less helpful as the Council has only 15 members and may be prevented from adopting a draft resolution by a negative vote from a permanent member; and one needs to consult the explanatory statements made before or after the vote to establish whether the members expressed their view on relevant paragraphs. Even then, as the Council only comprises 15 members, one would have to see whether any legal views expressed are shared by States more generally (for instance through consulting GA resolutions adopted later on; note for instance that GA Resolution A/RES/56/1 condemning the 9/11 attacks and GA Resolution A/RES/56/220A on Afghanistan which condemned the use of Afghan territory for terrorist activities, unlike SC resolutions 1368 and 1373, do not mention the right of self-defence).

  8. Apologies: My first word in the comment above should of course have been Kristen.

  9. Kristen,

    I have two questions rather than comments.

    First, are members of the Security Council representing States when they deliberate and vote? Or is it that once on the Security Council, while we might say that ‘Australia voted …’, would it be better to say ‘the representative from Australia voted …’? I realise it is different, but I broadly have in mind how judges on the ICJ, even the ad hoc ones, do not ‘represent’ their respective States. Shouldn’t members of the Security Council be representing all member States?

    Second, you write “P5 would presumably be big players in determining custom”. Why is that? Because they are the P5? Because they are ‘big’ States (but compare France to India, the UK to Germany)?

    Thanks for your post and I especially look forward to your study on the UNSC, law making and armed conflict.

  10. A general query rather than a comment:
    I was wondering whether the fact that when SC issues binding resolutions (including the legislative ones like Res. 1373) which the States are universally bound to execute (superseding any other treaty obligations), could in any way be indicative of a state practice and a corresponding opinio juris sive necessitatis (since States are legally obligated) and thereby constitute formation of customary international law?

    Thank you for the post and looking forward to any answers.

  11. I agree with André in general terms.
    I would add one simple question: have you realizad that, when voting, the SC members deliberately reduce the legal scope of their decisión acting in an ad hoc basis? Verbatim records are more than illustrative!

  12. Is not mentioning the role of the UNSC in the formation of custom more an act of “legal correctness” than a real observation of what really occurs? Would it be “legally polite” to recognize the role of 5 + 10 “special” states in the formation of international norms biding to them and the rest of states? Would not it be more accurate to just observe that, obviously the UNSC can be seen as providing state practice and the UNAG, explicitly by stating definitions or implicitly by not reacting, the opinio juris? One good example is the prohibition of aggression, which had been “practiced” through UNSCRs and its application of article 2(4), a definition “approved” by the UNAG (Resolution 2625 and especially 3314). … In 1966, the ILC recognizing that article 2(4), “together with other provisions of the Charter” as modern customary law…(ILC Yearbook 1966, vol. II, p.247).

  13. Thanks all for these fantastic comments. A few thoughts now, more to come. First, I think [with due regard to Andre’s comments] some of these comments demonstrate that the Council is generally presumed to possess some potential to make customary law: Hostage notes the premise behind theRepertoire, and on the flip side, Kenneth notes concern with regards to the precedential impact of statements in the piracy resolutions, and efforts to clarify that the Council is NOT making customary law. These are relevant to the baseline potential of the Council’s potential to influence CIL.

    Nonetheless, the Council’s law making powers are controversial. Andre I agree (and noted in the blog post) that there is push back on the Security Council as legislator, perhaps due to the fact that the COuncil can “overclaim” its law making powers in this regard. Yet, I believe the Council can legislate, given the structure of Chapter VII and the combination of Arts. 103 and 25 – although certainly there are limits on appropriate subject matter. (Thank you, Ori). One thought as an aside on this issue: I think the Council’s resolutions on counter-terrorism have been generally viewed as helpful in overcoming gaps in the law – I say more about this below – but I note James Crawford in his recent book – The General Part – on State Responsibility makes the point that this is a method to overcome some of the limits of the attribution articles (ie, the effective control standard) under the Articles on State Responsibility.

    Andre your nuances on the ICJ decisions on the status / value of GA resolutions are well taken and much appreciated. I will come back separately on the question of voting patterns, as I think this raises a series of very important questions.

    Ian, as far as I see, Security Council states vote as representatives of their own states. Particularly the P5. The exception to this is perhaps the non-permament 10 which are elected on the basis of regions, and may have other agendas. I don’t think ICJ judges work as an analogy because there, the judges are appointed as representatives to an independent judicial institution, which the Security Council is not. I say the P5 are big players in custom not because they are the biggest in terms of population, but because I see them as countries that carefully assess the developments of international legal rules, and are usually quite careful about what they support or object to, largely, I surmise, because they want to preserve their place as a “persistent objector” if necessary. However, this does not mean that other countries are not equally as careful, just that I think that the P5 have a vested institutional interest in the development of legal rules that makes them more careful. Sarah in this regard, I think the Council does have exceptional powers under Art. VII, so its not a question of being polite, but rather an assessment of power of Arts. 25 and 103.

    Burjis, your question raises the issue of “instant” custom. I don’t think a Security Council resolution could do it – instead, I would view resolutions like 1373 as gap fillers, overcoming some of the lacunae in the law that have not been filled by treaties or controversies over the definition of terrorism.

  14. Response… some of these comments demonstrate that the Council is generally presumed to possess some potential to make customary law: Hostage notes the premise behind the Repertoire, and on the flip side, Kenneth notes concern with regards to the precedential impact of statements in the piracy resolutions, and efforts to clarify that the Council is NOT making customary law.

    No, the practice of publishing a Repertory began with the League of Nations. I don’t think anyone thought its organs could make laws. I was thinking more along the lines developed by Judge Elihu Lauterpact in the Bosnia case or Alexander Orakhelashvili’s article on resolution 242, which held that the Security Council is unconditionally bound by the principles of customary international law reflected in the UN Charter. So the SC’s Repertoire, and the Repertory of Practice of United Nations Organs, provide official interpretations of the rules of the Charter and present evidence regarding the way the organs apply them or how they have governed decisions taken in the various organs. Likewise, I don’t think that the General Assembly makes customary law per se, but I think it can deliberately compile or codify existing customary rules in a declaration and that resolutions can, and should, reflect customary international law and the rules of organization and functions laid down in the Charter.

  15. I would state that some GA resolutions address law or make conclusions about the application or breach of law and, therefore, can provide relevant indicia of opinio juris — but they are not “practice” as such or at least relevant practice with respect to the formation, continuation, or termination of CIL. The same would apply regarding some SC resolutions. I would add to neither institutional arrangement “legislates” as such, even though these institutions and numerous other actors are constantly involved in processes of normative identification, formation, invocation, application, review, etc.
    And yes, the SC is bound under the UN Charter re: the purposes and principles of the Charter in view of arts. 24-25, 55, etc.

  16. Dear Kristen, thank you for your response to my comments…Do you mean the ILCommission’s recent report does not mention the SC in the formation of custom because it has exceptional powers?

    Would it be possible to propose that the SC’s legal work, and its careful choice of words, shows state practice, because its resolutions are binding making states’ attitude relevant of their position towards norms, and that GA’s legal work shows only opinio juris, because its resolutions are not binding making states’ positions only a recognition of existing norms? … Obviously in a perspective where customary law is the principal source of international law that treaty obligations only codify, where “pacta sunt servanda” is a customary norm…

  17. Re: I would state that some GA resolutions address law or make conclusions about the application or breach of law and, therefore, can provide relevant indicia of opinio juris — but they are not “practice” as such or at least relevant practice with respect to the formation, continuation, or termination of CIL.

    I think that there might be some narrow exceptions to that with respect to the customary multilateral steps regarding the creation of states in international organizations. LoN or UN resolutions containing mandate or trusteeship instruments regarding safeguards for minorities were based on the practice of the Concert of Europe and the concept of granting title to a territory or recognition on the basis of acceptance of a minority rights agreement, such as the provisions regarding Serbia, Montenegro, and Romania in the Treaty of Berlin 1878. The Versailles Peace Conference established a single Committee for Minorities and the Creation of States to deal with those situations. Clemenceau attached a note to the Polish Minority Treaty which explained it was a long standing customary practice connected to the creation of new states through the assistance from the international community. So a LoN or UN resolution could contain binding minority protections or safeguards or demand declarations from the parties concerned, that were considered tantamount to legally binding treaties.

    For example, the minority protection plan contained in resolution 181(II) placed fundamental rights under UN guarantee and was cited in the GA request and the ICJ advisory opinion as a relevant resolution that was the source of the UN’s permanent or on-going responsibility for the question of Palestine. It was included in a catalog of minority treaties and instruments published by the Secretary General in 1950. The plan for Palestine was the only instrument that wasn’t deemed to be affected by the dissolution of the League of Nations. See E/CN.4/367, Date: 7 April 1950, Chapter III The United Nations Charter And The Treaties Concluded After The War, resolution 181(II) of 29 November 1947, “The Future Government of Palestine”, pages 22-23

    I think the Dayton Accords were circulated as documents of the General Assembly and that the UN and EU conditioned recognition of the new states on its guarantees regarding rights and protections of national minorities.

    In the Namibia case, General Assembly resolutions that terminated the Mandate; explained that there was no other basis for South African administration; and which placed Namibia under direct UN administration in accordance with Articles 18, 73, 80, 81, and 85 was an example of the General Assembly laying down the law and implicitly asking the Security Council and other UN organs, including the ICJ, to enforce its “decisions”.

  18. voting at the U.N. in favor of a resolution and/or the creation of a resolution cannot be the relevant state “practice”. Relevant practice will involve practice complying with, shifting from, violating, and so forth a relevant norm.

  19. Many thanks to Hostage and Jordan for their insights.

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