Formation of Custom and the Inherent Powers of the Special Tribunal for Lebanon

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Yesterday the STL Appeals Chamber issued its first substantive decision (h/t Bill Schabas’ blog), penned by Professor Antonio Cassese, who was not only the presiding judge but also the judge rapporteur in the Chamber. The decision delves in great detail into the concept of inherent powers of international courts and tribunals, and is strongly reminiscent of the ICTY Appeals Chamber’s first decision in Tadic, over which Judge Cassese obviously also presided.

Expansive invocations of inherent powers have not come without controversy. The STL decision, although ostensibly dealing with a very technical matter of the access of a potential suspect to documents in his case file, is well worth the read on several points of principle. I was particularly struck by the Appeals Chamber assertion (para. 43 of the decision) that a rule of customary international law now exists to the effect that international courts and tribunals possess an inherent jurisdiction, which confers on each of them the power to determine the scope of their own jurisdiction (competence de la competence; Kompetenz-Kompetenz). I was even more struck by how the Appeals Chamber went on to prove that such a customary rule existed (para. 47):

The extensive practice of international courts and tribunals to make use of their inherent powers and the lack of any objection by States, non-state actors or other interested parties evince the existence of a general rule of international law granting such inherent jurisdiction. The combination of a string of decisions in this field, coupled with the implicit acceptance or acquiescence of all the international subjects concerned, clearly indicates the existence of the practice and opinio juris necessary for holding that a customary rule of international law has evolved.

Fantastic, no? Note how custom now apparently equals what tribunals say is custom, plus lack of objection by anyone else. Note also how the Appeals Chamber does not refer to state practice and opinio juris, but to practice pure and simple, as well as to the ‘lack of any objection by States, non-state actors or other interested parties‘ and the ‘acquiescence of all the international subjects concerned.’ Hardly an orthodox account of the formation of custom!

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Julian Arato says

November 11, 2010

Fascinating opinion. Many thanks for your post and analysis. One point strikes me: the way the Tribunal has proven the existence of custom here is more reminiscent of the way the ICJ (among others) have proven the transformation of the constituent instruments of international organizations under the rubric of subsequent practice (VCLT 31(3)(b)). Some examples that come to mind are the ICJ's AO's in Certain Expenses and Namibia, where the Court found that the sustained practice of the IO organ, coupled with acquiescence of the States Parties, was sufficient to demonstrate that the instrument had been reinterpreted on the basis of the "subsequent practice of the parties."

This move, in Certain Expenses at least, was subject to a scathing critique by Judge Spender in his separate opinion, who decried this use of the interpretive technique as an end run around the requirement of actually taking state practice into consideration when relying on the "subsequent practice of the parties" in interpretation. But the majority opinion carried the day - the technique of interpretation was incorporated into the VCLT with no mention of the mechanics of its application with respect to IO's, and it has been used since then by the ICJ in just the same way - paying attention only to the practice of the organ so long as there is no outright objection by the states.

Part of the worry then was IO's using their constituent instrument treaties as a way of making an end run around the traditional modes of international law making (treaty, treaty-amendment, and the formation of custom). What's fascinating here is that the Tribunal seems to be making a parallel move with regard to the formation of custom, attempting to transform and expand the role of IO's (Courts in this case) in CIL formation and reducing the role of States to the passive position of presumed consent "so long as they don't object." And I suspect you'd agree that its a somewhat open question whether Judge Cassese and the Tribunal are right or wrong.

This is not to attack the opinion on the "substance," regarding the judicial kompetenz-kompetenz of international courts and tribunals, logically, philosophically, or even the position that it is a correct statement of the law (though as a general statement about all international courts and tribunals it will likely raise some more eyebrows). But it is at the least very interesting to read the Tribunal's perception of its role, and the role of IO's by inference, in the formation of custom.

(In case there's any interest, I'll take the opportunity to plug a paper I have on SSRN, coming out in LPICT later this year, comparing subsequent practice and evolutive interpretation that deals in part with the move I've described above regarding developmental treaty interpretation in international organizations - )

jpaust says

November 11, 2010

With respect to the formal and informal roles of various non-state actors in the past and/or their rights and duties, including natural persons, a company, corporation, union, vessel, court-house, insurgent, belligerent, tribe, free city, people, and nation, a new draft article is posted on ssrn:

As the article begins:
For centuries, there have been vast numbers of formally recognized actors in the international legal process other than the state, although far too many assume incorrectly that traditional or classical international law had been merely state-to-state and that under traditional international law individuals and various other non-state actors did not have rights or duties based directly in international agreements or customary international law. Even today, invidious consequences occur when judges cling to manifestly ahistorical assumptions about international law and rule erroneously that “customary international law consists of only those norms that are ... obligatory in the relations of States inter se.” [2d Cir. panel, Kiobel case, 2010] This article seeks to explode such a false and inhibiting myth by identifying a large number of such actors from each inhabited region of the globe and a number of specific forms of formal participation from the 1700s through the early 20th Century when, according to myth, state-oriented positivism allegedly achieved complete and universal acceptance and denied the existence of any status, role, right, or duty of any non-state actor.

Accursius says

November 12, 2010

Strangely enough Cassese did quarrel with ICJ's virgin birth of "effective control", notwithstanding the lack of state practice or opinio juris (although it wasn't opposed by states either, except before the Court itself). Also, Marko, except in "Follow up..." you yourself haven't doubted the legality/legitimacy of that one.

Mihai Martoiu Ticu says

November 12, 2010

As Professor Paust writes in his paper it might just be a myth that customary international law (CIL) is made only by states.

Christiana Ochoa claims that (during Alien Claims Tort Act litigations) individuals “enter into discussions with the particular judges or panels of judges hearing their claims about what the CIL of human rights is and what it ought to be. In so doing, they also provide valuable information to nation-state representatives, the judiciaries of other nations, and to multinational bodies about which norms civilized people believe form the CIL of human rights.”[1]

International Courts can create CIL. Maurice Mendelson, dwelling on the meaning of the term “determination”, in Article 38 (1)(d) of the ICJ-statue, he discovers that one of its meanings is that of “creation”, of “laying down”[2].

Karol Wolfke is certainly positive about the ICJ creating CIL: “It might be said that whoever accepts the authority of a court must of necessity accept a minimum of its competence in the creation of customary international law.”[3] and ICJ’s “contribution to the formation of customs is indisputable,” [4] In a footnote,[5] he gathers together ICJ pronouncements asserting its own role in the formation of CIL.

European Court of Human Rights decided recently that there was a “right to a healthy and protected environment that is a part of the right to the respect of the private and family life”,[6] thus adopting the argument of a private individual. The court is only supposed to decide on the provisions of the convention and there is no “right to a healthy and protected environment” enshrined in that. Thus one could argue that an individual's private act leads to new human rights, and, therefore, to a new CIL, through a binding decision on the part of an international court.

Louis Sohn claims that governments do not really create CIL themselves. Instead they ask “silly professors”[7] their opinion, or consult their work, in order to discover the international law. He submits “that states really never make international law on the subject of human rights. It is made by the people that care; the professors, the writers of textbooks and case books, and the authors of articles in leading international law journals.”[8]

“It is, however, well-known, for instance, that captains of private vessels, fishermen and pearl divers fishing in their own name in certain areas of the sea contribute, by their conduct, to the development of international customs concerning open sea, territorial sea, the continental shelf, etc.”[9] Wanting to extend its territorial waters and to protect the pearl beds from exhaustive exploitation, Australia discovered that Malay and Indonesian native divers might have acquired rights originated from their use “without formal protest...from time immemorial”[10].

Bankers “often go against positive law. What definitely give[sic] the customary rule which is created by the repetition of their acts the obligatory force of a legal rule”[11]

Till Müller also concludes that “individuals, NGOs, and TNCs,… are greatly contributing to the creation of customary law.”[12]

[1] Christiana Ochoa, "Towards a Cosmopolitan Vision of International Law: Identifying and Defining Cil Post Sosa V. Alvarez-Machain," U. Cin. L. Rev. 74, no. 1 (2005), ———, "Individual and Customary International Law Formation, The," Va. J. Int'l L. 48, no. 74 (2007).

[2] Maurice H. Mendelson, "The Formation of Customary International Law," Recueil des cours: vol. 272. (1998). p.200 p.202 Note 95

[3] Karol Wolfke, Custom in Present International Law. p.75

[4] Ibid. p.76

[5] “The Court itself stated in its Judgment of 1984: ‘... the Court's Judgment... in the North Sea Shelf cases... has made the greatest contribution to the formation of customary law in this field [Continental shelf].’ Delimitation of the Marine Boundary in the Gulf of Maine Area. ICJ Reports 1984, p. 293. See also, e.g.. Fisheries Jurisdiction case, ICJ Reports 1974, p. 23; Continental Shelf (Tunisia/Libyan Arab Jamahiriya) Judgment, ibid., 1982, pp. 43, 44, 60, 61 and 74” Ibid. p75

[6] ECHR 2007, Tătar v. Romania, (application no. 67021/01)

[7] Louis B. Sohn, "Sources of International Law Iii: The Status and Future of the Customary International Law of Human Rights," Ga. J. Int'l & Comp. L. 25 (1995). p.401

[8] Ibid. p.399

[9] D. P. O. O'Connell, "Sedentary Fisheries and the Australian Continental Shelf," Am. J. Int'l L. 49 (1955).

[10] D. P. O. O'Connell, "Sedentary Fisheries and the Australian Continental Shelf," Am. J. Int'l L. 49 (1955). p.188

[11] Lazare Kopelmanas, "Custom as a Means of the Creation of International Law," Brit. Y.B. Int'l L. 18 (1937). p.150. see also at p.151: “all the subjects of law…contribute to the formation of international custom.” See also at p149: “On the other hand these conditions are present when the international relations connect individuals belonging to different national organizations, even if the organs of the state take no part. This is why we are able in fact to find the existence of customary rules worked out by simple private individuals.”

[12] Till Muller, "Customary Transnational Law: Attacking the Last Resort of State Sovereignty Conference on Democracy and the Transnational Private Sector," Ind. J. Global Legal Stud. 15 (2008). p.47

Marko Milanovic says

November 12, 2010


Thank you very much for the comments, they are most helpful. I also look forward to reading your article on evolutionary interpretation soon.


I'm not sure I follow - could you perhaps clarify your comment a bit? The ICJ is certainly known for making oracular pronouncements from on high of what customary law in its view is, without adducing much evidence to support its holding (this again happened e.g. in the Bosnian Genocide case regarding the various tests of attribution, even though the Court was in my view correct in what it decided). The Court has also employed different standards for establishing custom; a cynic would say that they are more stringent (e.g. near universal practice etc) when the Court doesn't want to find custom, and lax when it does. Is this what you had in mind? If so, I fully agree.

Jordan and Mihai,

I protest, yet again, at being labeled a doctrinaire (if not in so many words)! :) As far as I'm concerned, the identity of persons entitled to participate in the formation of custom is essentially a matter of political fact, flowing in Hartian terms from whatever the rule of recognition is in contemporary international law. It may be that at some point in the past non-state actors did participate in the formation of custom;* it may be that they will do so in the future. But this is certainly not the orthodox view, as e.g. encapsulated in Art. 38 of the ICJ Statute and 90% of textbooks on the market, and I would be hard pressed to find a judgment of any other international court or tribunal that would be as emphatic as the STL one in this regard.

*When I say 'participate', I mean this very formally in the sense of what the SOURCE of law is considered to be. It is of course true that judgments of international courts have always been influential in determining custom. But they were generally regarded as subsidiary sources, as evidence of custom (as in Art. 38 of the ICJ Statute), not as THEMSELVES creating custom. The distinction is perhaps often a fiction, but again I have never before seen a court assert, as the STL Appeals Chamber did, that custom can be created solely by judicial practice absent a specific protest by states.

Birgit Schlütter says

November 12, 2010

Dear all,

I just saw this intriguing thread and thought I contribute with four small comments on how courts, including the ICJ, identify the formation of new customary international law. The decision of the STL is noteworthy, and it mirrors to some extent the current methods of identifying customary international law. I have only looked at the ICJ and the ad hoc tribunals for the Former Yugoslavia and Rwanda, but from their jurisprudence it seems that:

1. The ICJ, as well as the ad hoc tribunals do refer to ‘non-state evidence’ when identifying new customary international law. The most intriguing example is the work of the International Committee of the Red Cross (ICRC), which has been identified by all three courts and tribunals as being indicative of an opinio juris. For example, the ICJ pointed towards such a possibility in the Wall advisory opinion (para 97). The ICTY regularly refers to the ICRC`s commentary on the Geneva Conventions as well as to its Study on Customary International Humanitarian Law when it considers the formation of new customary international law (compare Prosecutor v. Tadić, Interlocutory Appeal, Case No. IT-94-1-AR72, 2 October 1995, para. 109; Prosecutor v. Prosecutor v. Hadzihasanovic, Appeals Chamber Judgment, Interlocutory Appeal on Rule 98 bis, Case No. IT-01-47-AR73.3, 11 March 2005para. 30; Prosecutor v. Stakić Appeals Chamber Judgment, Case No. IT-97-24¬-A, 22 March 2006, para. 300).

2. There are indeed very few judgments where a rule of customary law was established by reference to international jurisprudence. One is the Tadić Appeals Chamber Judgment (Prosecutor v. Tadić, Appeals Chamber Judgment, Case No. 94-1-A, 15 July 1999, para. 271) where the Appeals Chamber almost exclusively referred to the judgments of the (international) military tribunals established after WWII when establishing the customary rule that crimes against humanity could be committed for purely personal motives.

3. Considering the current methods employed by, for example the ICTY and ICTR, or the ICJ for that matter, it is indeed very difficult to establish a clear distinction between methods of interpretation and methods of identifying a new rule of customary international law. The ICJ´s opinion in Certain Expenses is a good example. Sometimes, also the methodology used by the ICTY for the interpretation of a rule of international criminal law, is indistinguishable from the method, which it employs when identifying a new customary rule (see, for example, Prosecutor v. Krstić, Trial Chamber Judgment, Case No. IT-98-33-T, 2 August 2001, para 590). This is certainly worrisome and the courts and tribunals are well advised to reconsider the approaches they have developed so far.

3. It is simply a myth to believe that there exists but one approach to deal with the source of customary international law (and this concerns both the evidence and the actual method referred to). International scholars, the ICJ, the ICTY and the ICTR have all employed various methods when identifying customary international law. This is not worrisome per se, but it becomes worrisome, if those methods conflict with the requirements of legal certainty or legal clarity, or the prerequisites of the nullum crimen sine lege principle.

If you are interested:

Guy says

November 12, 2010

Dear Marko,

Nice post, thank you. I have only one question - why do you consider it strange for a tribunal to refer to 'practice' rather than to 'state practice' in a field of law that does not apply to states? How would state practice in this specific field of inherent jurisdiction of non-state courts, for instance, work? It would seem logical - and not contradicted by state practice and opinio juris to my knowledge, that rules on insurgents, on international organizations, and on other non-state actors are also, or even primarily, formed by practice of these non-state actors. Article 38 is merely a statement of the law the ICJ is meant to apply in controversies that were thought to be mainly amongst states at the time of the PCIJ and ICJ creation - one might understand the language of those Statutes with that particular situation in mind and not as a general restatement of how custom should be conceived.
Anotehr question: do you have a take on the substance of the decision? Do you disagree that international courts have inherent jurisdiction over what the STL says they have, be it by virtue of custom or maybe a general principle of law?

Marko Milanovic says

November 12, 2010


Thank you for the most helpful comment. Well, I agree that it is hard to see how a customary rule based in state practice could evolve with regard to an issue that usually does not involve states directly, as with the inherent powers of international tribunals (although it could, if the tribunal asserts a power vis-a-vis states). But this begs the question whether customary law is indeed the proper body of law in which to find such rules; to my mind general principles of law look like a far more promising route.

On the other hand, look at both how the Appeals Chamber and you in your comment proceed in assessing the formation of a customary rule: (1) the existence of an alleged rule is asserted by a tribunal; (2) the rule is established if no contradictory state practice and opinio juris is found to exist. I am not saying that this is necessarily WRONG; but it is DIFFERENT from how custom is usually conceived of in international law. And it has significant practical consequences for state behaviour, in that now they need to be ever vigilant and protest against the formation of alleged customary rules even if they do not directly concern them at the time.

As for the issue of whether non-state actors have a rule-making capacity in international law, I would strongly dispute that this has anything to do with logic. It is rather a question of authority and legitimacy, of who the rule of recognition sees as capable of participating in the law-making process, and in what way. It is also a question of practicality, e.g. is it even possible to (say) ascertain the 'practice' of 7 billion individuals, or of an undefined number of a nebulous category of non-state actors.

In that regard, there are non-state actors and non-state actors. Some of them, such as IOs or the ICRC, have been created or recognized by states as having a distinct international capacity. That some non-state actors can participate in the creation of law does not mean that all of them or most of them can. It is particularly instructive, for example, how the ICRC approached the question of 'practice' in its customary IHL study:

See in particular points (v)-(vii). As you will see, the ICRC was justifiably cautious in assigning some limited normative content to non-state practice, e.g. with regard to armed opposition groups - and even this was not uncontroversial.

As for your final question re the substance of the decision, I would prefer to remain agnostic. I really have not studied the question of inherent powers in much detail, and I am quite comfortable in not having an opinion on matters I don't know enough about.

Guy says

November 12, 2010

Thank you very much for your insightful comments. I still think logic is a useful tool of interpretation when dealing with legal theories and text (after all, the way custom is formed is just a theory, not a fact).
The fact that the STL is an independent (non-state) actor is one of the assumptions upon which this decision appears to be based. It would be interesting to discuss the international personality of such international tribunals that are not UN organs (unlike the ICTY and ICTR, which clearly are).
On the formation of new international law rules, I subscribe more to the view that custom is better described as a process of claims and counter-claims slowly (but at times not so slowly) shaping the normative environment within which actors ... well, act. The ICJ Statute view is far too remote from what actually occurs in practice. But I see your general point and am grateful for your clarification.

Vladyslav Lanovoy says

November 12, 2010

I found very interesting your post, however this decision of the STL comes as no surprise in light of the recent approach of international courts and tribunals to custom. Suffices to read recent judgments of the ICJ, notably Bosnia Genocide case and Costa Rica v. Nicaragua. As Wittgenstein used to say "worüber man nicht sprechen kann, darüber muss man schweigen". The courts simply cannot remain silent even when clearly they cannot sustain the existence of the customary rule or maybe they simply prefer to be criticized for lack of rigorous reasoning rather than falling into the Nuclear Weapons AO scenario. As a general point, I think we can all agree that the theory of sources is clearly outdated. As an example, I am currently writing my thesis on the concept of complicity in the law of international responsibility. To be sincere, I came to the stage where I question its existence to begin with, not to say its customary international law character as the Court laconically framed in the Bosnia Genocide case. Producing a secondary norm merely on the basis of diplomatic allegations when many diplomats have no legal background to begin with does not necessarily correspond to the emergence, even less, crystallization of a legally binding norm. Even less so, assuming the existence of a norm merely on the basis of the practice of the tribunals, non-state actors, etc. While international law has somehow overcome the tension between co-existence and co-operation, it seems rather immersed in the Virally's double rapport de normativité. Oiling the wheels of custom, to borrow the words of Higgins when referring to another equally conspicuous entity of equity, seems an appropriate way out but clearly a way too simplistic one for the courts of law.

Tamás Hoffmann says

November 12, 2010

Dear Marko,

It is a fascinating judgment indeed. I have recently written a piece about the influence of Cassese on the development on the customary norms of non-international armed conflicts.
I argue that with the Tadic Appeals Judgment he effectively created a new body of customary international law, with the assistance of the authority of the ICTY and relying on essentially moral arguments.
However, in Tadic, he disguised this essentially law-creating argumentation in an ostensibly rigorous analysis of state practice and opinio juris.
It seems that he has reached the point where he does not even regard it necessary to disguise revolutionary ideas in orthodox terminology. However, I have serious doubts that he could pull off a fundamental reinterpretation of the creation of customary international law...

If anybody interested in the article, it is accessible at:


jpaust says

November 12, 2010

And isn't it interesting that the drafters of the Statute of the ICJ know how to use the word "state" (art. 38(1)(a)), but chose not to do so with respect to customary international law -- somehting that I address in my new article in footnote 87.
By the way, some of the treaties between states and non-state actors are still operative and the duties of individuals under treaty-based and customary international law are alive and well. The main point is that our awareness of the actual history of international law, and apparently its present operation, is remarkably incomplete. There are varied and rich patterns of participation (both formal and informal). I believe that those who state that "traditional" or "classical" international law had merely been state-to-state should revise their textbooks and treatises so as not to look so foolish. I think that the myth has now been exploded!

Dov Jacobs says

November 13, 2010

Hi Marko,
I share your astonishment at the argumentation. I posted on the issue this afternoon. In addition to your remarks on the conditions for customary law, I also suggest that there the two sentences of paragraph 47 are not entirely coherent. Is the "general rule" in the first sentence in the first part, the same as the "customary law" in the second?

More importantly, I actually think the STL laid what I call in my post a "semantic trap" for us. By using the words "customary law", it has tricked us into debating the conditions of custom, where in fact, what they describe has nothing to do with customary law in the first place. I know it's a thin line between evolution and change of nature, but there comes a point where if I take my fridge, put an engine, four wheels and a steering wheel on it, I could still call it a "fridge" of course, but we all would know that it is now a car...

Any thoughts on that?

Take care,


Marko Milanovic says

November 13, 2010


Thanks for the comments - and your paper is excellent.


Agreed! It's a car, not a fridge.

Sergey says

November 14, 2010

This paragraph in the decision leaves me wandering whether international law is slowly transforming into common law?
In many instances international courts while "applying" customary international law or "interpreting" treaty do in fact create law. It can be argued that this (in light of the topic one may say inherent) power is vested upon them by the States, which decide to create those courts.
Besides, one can argue that acquiscence also plays a role in formation of custom. Certainly if a State openly takes certain actions (or interprets a treaty in a given way) and noone objects to it, this could be argued to evidence custom. So perhaps the same can be said where a statement is made by an interpreter (i.e. a court)? We have obviously seen examples of States disagreeing with interpretation of treaties by the tribunals vested with power to interpret them (take famous NAFTA interpretation or reaction of some States to Maffezini v. Spain).
This being said I do agree that the tribunal need not have relied on customary international law as the basis for conclusions on procedural issues which it made.

Max says

November 21, 2010

On the decision itself, it's all a bit confusing for us mere mortals out here: art 26 of the Statute says that the Appeals Chamber "shall hear appeals from persons convicted by the Trial Chamber or from the Prosecutor ...".

It's all very well to believe that "it would not make sense" for the Appeals Chamber to determine procedural issues after a merits determination - and to observe that the Chamber "will not normally" consider interlocutory matters, but that is - surely - simply a matter put beyond question by the terms of art 26.