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ESIL Reflection – The Altering Rivers of Customary Worldwide Legislation – The Interpretative Course of as Flux – European Society of Worldwide Legislation

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Vol 11, Problem 5
Editorial board: Federico Casolari, Patrycja Grzebyk (editor-in-chief), Ellen Hey, Man Sinclair, and Ramses Wessel
Başak Etkin* (Université Paris II – Panthéon-Assas)




Heraclitus – portray by Raffaello Sanzio da Urbino (cc)


Herakleitos by no means really stated “You can’t step into the identical river twice”. In Plato’s Cratylus (402a), Socrates quotes Herakleitos to Hermogenes as having stated so. The well-known line is subsequently merely heard by the grapevine.


  1. The Analogy


Analogies (and metaphors) are quite common in IL[1], and if used nicely they are often a part of the rational reconstruction of a notion. The river analogy is especially helpful for our understanding of norms and interpretation, particularly that of customary (worldwide) regulation. It exposes the circulate of customized in a surprisingly easy manner, which then highlights key variations with treaty regulation in addition to a number of the many inconsistencies of the two-element strategy. Serious about customary guidelines as a flux reveals a few of these neglected elements.

What Herakleitos really stated in regards to the river is considerably disputed: three of his fragments appear to say the thought of the river, however fragment 12 is broadly accepted as the real river fragment.[2] Alas, due to the confusion across the competing fragments, his doctrine is broadly misunderstood. The river doctrine is extra in regards to the unity in change reasonably than the fidelity of change, as offered in fragment 12.[3] David W. Graham explains that “some issues keep the identical solely by altering. […] On this studying, [Herakleitos] believes in flux, however not as harmful of fidelity; reasonably it’s, paradoxically, a mandatory situation of fidelity, not less than in some circumstances (and arguably in all)”.[4] What makes the river a river is the fixed altering of waters.[5]

So is the case for customary worldwide law¾and doubtlessly even for all authorized guidelines extra usually. One can not adjudicate the identical customized twice. As a unity, the customary rule R which we observe at time t1 is identical customary rule because the one which we observe at t2; as a range, since its contents preserve altering, it isn’t the identical.[6]

As an example, at instances t1 and t2, a choose could also be adjudicating the identical rule R, as in, referring to the identical supply with out figuring out a brand new customary regulation. But, between these two moments in time, the exact same rule R might have been topic to interpretation by different authorities like states or worldwide organisations, its penumbra lowered and core expanded. Thus, the choose can be referring to the identical rule R, though its contents would have modified within the meantime. The rule is subsequently the identical and never solely in identify, on condition that it’s seen as in continuity, but completely different all of sudden. As this form of change is inherent to the lifetime of a rule, as is the circulate to a river, it’s this fixed change or flux that makes it a unity.[7] As an example, within the Jurisdictional Immunities of the State case, the Worldwide Courtroom of Justice determined that an accusation of jus cogens violations wouldn’t deprive a state of immunity.[8] From that time on the customary rule on immunities had modified, and future circumstances, such because the proceedings instituted by Germany towards Italy on 29 April 2022, now must take this into consideration. The rule is identical, that of state immunity, but completely different, with the addition of a brand new side.

So, what does this imply for interpretation of customary guidelines?

Firstly, it signifies that interpretation of a (customary) rule is merely part of its flux and that each one interpretation is considerably constructive. The traces between modification and evolution by interpretation are blurred, each indicating a kind of change¾with the latter implying considerably a way of route, given the bizarre that means of the time period ‘evolution’. Deciphering a (customary) rule is essentially altering the rule, by together with or excluding a sure side of it. As might already be clear, change right here is known in a particular however very broad manner. Some argue that interpretation doesn’t change the rule however merely reveals it. I, alternatively, would counsel utilizing the phrase ‘change’ for the end result of all interpretative processes. In my opinion, the true content material of the rule is indeterminate earlier than it’s interpreted, whereas the thought of a reveal means that it was mounted beforehand in an improperly deterministic style.  Whereas interpretation is finished in an lively sense by an actor invested with the authority to interpret the rule, be it for example a court docket or a state, change (as an umbrella time period for modification, evolution and past as used on this paper) is the results of that course of, and all of those phenomena contribute to the rule’s flux.

A seemingly synthetic division of what’s understood by interpretation of customary worldwide regulation will permit for some clarification: is there interpretation of the customary rule unbiased from the interpretation of the 2 components that show its existence? There have to be, as a result of state apply and opinio juris usually are not the rule itself, they’re merely proof of the rule, or the microscope with which we observe it.[9] Even when the ILC calls them ‘constitutive’, the rule itself, already constituted, exists in a normative realm earlier than its preliminary remark, and should or might not be recognised by the court docket. [10] The rule, or its new interpretation, exists and doesn’t exist till the choose guidelines on the matter, as there may be simply no certainty on whether or not the rule will likely be recognized or not (and on which model of it will likely be chosen among the many many prospects). The issue right here is that as there isn’t a formal ascertainment of customized,[11] consequently the distinction between the existence of a customary rule and its content material is harder to determine. If the thing have been a treaty provision, the authorities would first look to see whether or not there was a treaty in drive after which to the content material of the rule. This two-step strategy could possibly be replicated for a customary rule as follows: firstly, if the customary rule in query has by no means been recognised earlier than a court docket or one other physique up to now, the authorities would first have to determine its existence in a quantifying method (“is there sufficient state apply?” and many others.). Then and solely then might questions round content material be answered; but establishing the existence by the 2 components would have already got prejudiced the content¾the apply and perception are essentially tied to a sure understanding of the rule. Considering or leaving out a specific behaviour or a particular perception in regards to the rule will essentially taint the ultimate product, because the proof offered to a jury would have an effect on the decision. Subsequently, in contrast to treaty regulation and as dictated by the flux of the river analogy, the existence/content material division considerably collapses, though this questionable distinction could also be helpful for theorising different points. Secondly, as soon as it’s recognized, there can be interpretation of the rule itself independently from the interpretation of the 2 components, which can even have an effect on the content material, in mild of its object and goal for instance. Deciphering the rule modifications it in an unknowable, even when not unforeseeable, method. Therefore, in all circumstances, interpretation is constitutive of content material, and basically the same train to identification. Particularly given the shortage of official phrases as in written regulation, there may be no bizarre that means to offer to the phrases, and subsequently all interpretative train of a customary rule will likely be constructive and constitutive of that means, reasonably than extractive of what that’s already there, as is perhaps the case with treaty interpretation. Interpretation thus performs a decisive function in each step of a customary worldwide rule’s life[12], including¾and possibly especially¾identification, as that is the closest second to an origin. Interpretation and identification are therefore¾while distinct¾intertwined in a single stream, which makes the flux a very appropriate analogy.

Lastly, as interpretation is intertwined with change, so may or not it’s with the identification of a brand new, separate, customary rule. The query is, at what level through the interpretative course of does the interpreter bifurcate the flux and generate a brand new rule? Treating customary worldwide regulation the identical as treaty regulation can be a authorized fiction, however interpretation of customary worldwide regulation can, whereas not replicating it mutatis mutandis, resemble treaty interpretation. In treaty regulation, the truth that the textual content stays the identical makes for a straightforward reply; one can not go past the text¾whatever meaning. Relating to customary worldwide regulation, alternatively, the reply is a sorites paradox. A customary rule can have a core and a penumbra identical to treaty regulation, however there isn’t a textual content to restrict the change that the rule goes by. By means of the incremental change the norm goes by à la sorites, the river analogy would imply that one single customary norm can develop into unrecognisable and fully completely different and nonetheless someway be the identical. Probably, a regulation of the ocean rule can flip right into a rule on jurisdictional immunities over time, as interpretation intertwined with new apply and opinio juris collectively in a double helix carry the norm to new dimensions.[13] Unbound by a treaty’s black letter confines, the customary rule is free to vary, within the above-mentioned ‘massive’ understanding of change. Nonetheless, change may be much less incremental and extra abrupt, during which case, in contrast to the incremental change à la sorites, the phenomenon can’t be defined just by the interpretative flux and a proportionally abrupt change in apply or opinio juris have to be established.


  1. The Limitations


Surprisingly, the river analogy attains its restrict when confronted with the query of time, the very factor it’s supposed to explain. Not like a river which begins at a supply and ends the place it joins one other physique of water, time has no starting and no finish. Thus is the case for customized, which partially exists past the confines of time. How so?

As talked about above, opposite to treaty regulation, there isn’t a formal ascertainment of customary guidelines, and it’s subsequently troublesome to pinpoint an actual begin date. Within the Chagos Archipelago advisory opinion earlier than the Worldwide Courtroom of Justice[14], the court docket needed to decide if the fitting to self-determination had crystallised in 1965, and determined that it had, with out giving the precise date when it did. To take action, the court docket went again in time to situate the rule by taking a look at its formal proof by the two-element strategy. Nonetheless, the 2 components are proof of the norm however not the norm itself, they’re merely how customary guidelines current themselves to us, simply as treaty regulation presents itself by the medium of a treaty in black and white. The norm these components translate into phrases, as in treaty regulation, are intangible and unobservable. What we will and do observe is the formal proof of customary guidelines, that are the 2 components. In the mean time of the primary formal proof, apply P by state S, the state claims that they’re obeying a rule that already exists. Subsequently, there’s a starting to the formal proof, however to not the norm itself.[15] Interpretation occurs in time and constitutes the flux, however the river analogy can not account for the timeless nature of customary guidelines qua guidelines that exist in an atemporal realm, because the paradox of timelessness clashes with the temporal interpretative rivers.

One clarification, as soon as once more resorting to historic Greek philosophy, is to think about customary guidelines as Plato’s summary objects, often known as Varieties. Just like the latter, customary norms exist outdoors house and time, and are totally non-physical. With a purpose to reveal them, we, worldwide legal professionals, invented the two-element doctrine. By means of apply and opinio juris we see proof of the rule, not the rule itself. This fiction permits us to situate the rule in time, as we reside in a temporal and spatial world, and thus was the case within the Chagos Archipelago opinion. The rule doesn’t have a proper starting[16], however its proof does. The comfortable discursive construction of opinio juris along with the sharp staticity of state apply convey the summary rule into the spatio-temporal world.

Possibly not a restrict, however a nuance that the river analogy misses is the route of match of customary guidelines. Course of match, as defined by speech act theorist John Searle, permits us to distinction instructions and assertions by the excellence between becoming a state of affairs to phrases and becoming phrases to a state of affairs. When making use of treaty regulation, it’s the state of affairs, the ‘world’, that has to suit the phrase (world-to-word) primarily, based on what has been determined and put within the exact phrases of a provision¾at least in an easier case the place the rule is merely utilized with out resorting to interpretation; in a extra advanced case, ‘world-to-word’ utility might not be black and white for the reason that contents of a treaty obligation can also change through the interpretative course of. In customary regulation, for the time being of identification, the route of match is reverse: phrases want to suit the world (word-to-world). The authority which decides {that a} customary rule already exists on this planet finds the phrases that can match that rule. In a way, that is just like how the 2 components translate an intangible norm into concrete proof. We should select the fitting phrases to translate the observable state of affairs on this planet into language that can describe the normative rule. Nonetheless, there’s a restrict to this clarification too. As soon as the customary rule is recognized and transcribed into phrases, then the route of match can not merely be word-to-world, but in addition world-to-word as after the second of identification we’re supplied with the phrases that the world is meant to suit. For the interpretative course of, one might say the route of match is doubled, because the decoding authority, whereas making an attempt to suit world to phrase, additionally matches phrase to world. In treaty regulation and likewise in customary regulation as soon as it’s recognized, adjudicating authorities take a look at the world to evaluate whether or not it matches the phrases. Nonetheless, particularly in evolutive interpretation, additionally they take a look at the phrases to make them match the world in its present state, and their declaration of what the rule now could be makes the rule exactly that¾which makes it a double route of match.


  1. Conclusion


Whereas not excellent, the river analogy is beneficial, not solely as a result of it places into phrases the flux that’s customary regulation, however particularly as a result of it helps present the cracks within the two-element principle. As the 2 components are merely proof of the customary rule, and within the absence of formal ascertainment, an extra effort is important to disclose the variations between identification, existence, modification and evolution, that are extra clear-cut in treaty regulation. What is definite is that each one interpretation generates change and contributes to the flux of the customary rule. Breaking from the confines of treaty regulation logic by learning the particularities of customary regulation, on condition that the latter doesn’t match the restraints of the previous, would permit us a greater understanding of the nebula that’s customary worldwide regulation.



[1] Gorobets, Okay., 2019. The Unity of Worldwide Legislation: An Train in Metaphorical Considering. Philosophy of Legislation and Normal Principle of Legislation, 2019(2), pp. 80-109; Cohen, H., ‘Metaphors of Worldwide Legislation’, in Bianchi A. and Hirsch M. (eds) Worldwide Legislation’s Invisible Frames: Social Cognition and Data Manufacturing in Worldwide Authorized Processes (OUP, 2021).

[2] The three fragments talked about are numbers 12, 49(a) and 91(a). T. M. Robinson is of this view, and based on D. W. Graham, Okay. Reinhardt, G. S. Kirk, M. Marcovich all agree. From Robinson, T. M., Heraclitus: Fragments: A Textual content and Translation with a Commentary [1987] College of Toronto Press:

Fragment 12: ποταμοῖσι τοῖσιν αὐτοῖσιν ἐμβαίνουσιν ἕτερα καὶ ἕτερα ὕδατα ἐπιρρεῖ (“As they step into the identical rivers, completely different and (nonetheless) completely different waters circulate upon them.”)

Fragment 49a: “ποταμοῖς τοῖς αὐτοῖς ἐμβαίνομέν τε καὶ οὐκ ἐμβαίνομεν, εἶμέν τε καὶ οὐκ εἶμέν” (“We step and don’t step into the identical rivers; we’re and usually are not.”)

Fragment 91a: ποταμῷ γὰρ οὐκ ἔστιν ἐμβῆναι δὶς τῷ αὐτῷ καθ ́ Ἡράκλειτον (“For, based on Heraclitus, it isn’t potential to step twice into the identical river.”)

[3] Within the 2017 movie directed by Luca Guadagnino, Name Me By Your Identify, based mostly on the novel of the identical identify by André Aciman, Oliver (the protagonist’s love curiosity who can be a graduate scholar) writes on this matter: “The that means of the river flowing isn’t that each one issues are altering in order that we can not encounter them twice, however that some issues keep the identical solely by altering”.

[4] Graham, D.W., “Heraclitus”, The Stanford Encyclopedia of Philosophy (summer season 2021 version), E. N. Zalta (ed.).

[5] Hume expresses the identical concept: “Thus as the character of a river consists within the movement and alter of components; tho’ in lower than 4 and twenty hours these be completely alter’d; this hinders not the river from persevering with the identical throughout a number of ages.” in D. Hume, A Treatise of Human Nature, reprinted from the Authentic Version in three volumes and edited, with an analytical index, by L.A. Selby-Bigge [1896] Clarendon Press,, p. 258. For a French expression of the identical concept: “Plus ça change, plus c’est la même selected” (attributed to journalist and novelist Alphonse Karr, 1808-1890).

[6] Tailored from Robinson, T. M., Heraclitus: Fragments: A Textual content and Translation with a Commentary [1987] College of Toronto Press, p. 112.

[7] On the dialogue about temporal components and the way objects persist, see: Hawley, Okay., “Temporal Components”, The Stanford Encyclopedia of Philosophy (summer season 2020 Version), E. N. Zalta (ed.); Merkouris, P., 2014. (Inter)Temporal Issues within the Interpretative Means of the VCLT: Do Treaties Endure, Perdure or Exdure? in Netherlands Yearbook of Worldwide Legislation, 2014(45), pp. 121–156.

[8] Jurisdictional Immunities of the State (Germany v. Italy: Greece intervening), Judgment, ICJ Experiences 2012, p. 99.

[9] Kammerhofer J., “Between Pragmatism and Disenchantment: The Principle of Customary Worldwide Legislation after the ILC Challenge” in Merkouris, Kammerhofer, Arajärvi (eds), The Principle and Philosophy of Customary Worldwide Legislation and Its Interpretation (CUP 2022), p. 19.

[10] See beneath on Plato’s Varieties.

[11] “Not less than theoretically, one can nicely show the existence of a rule by a proper evidentiary course of though the rule involved is ascertained by advantage of non-formal standards […]”, d’Aspremont J., Formalism and the Sources of Worldwide Legislation: A Principle of the Ascertainment of Authorized Guidelines (CUP 2013), p. 152, extra usually, see, 151-154.

[12] For a superb dialogue on customized’s inherent plasticity and the function interpretation performs at completely different levels of a customary rule’s life which underlie this evaluation: Chasapis Tassinis, O., 2020. Customary Worldwide Legislation: Interpretation from Starting to Finish. European Journal of Worldwide Legislation, 31(1), pp. 235-267.

[13] Totally different elements of a rule must develop (or not) relying on the case. As an example, the customary guidelines on immunities have been implicitly taken into consideration for the interpretation of the rule of unique jurisdiction of the flag state (a codification of customary regulation) not less than twice: M/V “Norstar” (Panama v. Italy), Judgment, ITLOS Experiences 2018–2019, paras. 216-218, 225; PCA, The ‘Enrica Lexie’ Incident, Italy v India, Award, Case No 2015-28 (21 Could 2020), paras. 524-527. If this side have been additional explored in future affairs, one can think about the customary rule on the unique jurisdiction of the flag state doubtlessly changing into a rule on immunities.

[14] Authorized Penalties of the Separation of the Chagos Archipelago from Mauritius in 1965, Advisory Opinion, ICJ Experiences 2019, p. 95.

[15] On the paradox of opinio juris, see: Lefkowitz, D., 2008. (Dis)fixing the Chronological Paradox in Customary Worldwide Legislation: A Hartian Strategy. Canadian Journal of Legislation & Jurisprudence, 2008(21), pp. 129-148; Besson S., ‘Theorizing the Sources of Worldwide Legislation’ in Besson and Tasioulas (eds), The Philosophy of Worldwide Legislation (OUP 2010); Maiko Meguro, ‘Distinguishing the Authorized Bindingness and Normative Content material of Customary Worldwide Legislation’, ESIL Reflections 6:11 (2017).

[16] For an additional tackle customary worldwide regulation breaking the limitations of time and house, see d’Aspremont J., ‘The Customized-Making Second in Customary Worldwide Legislation’ in Merkouris, Kammerhofer, Arajärvi (eds), The Principle and Philosophy of Customary Worldwide Legislation and Its Interpretation (CUP 2022).


Cite as: Başak Etkin, ‘The Altering Rivers of Customary Worldwide Legislation – The Interpretative Course of as Flux’, ESIL Reflections 11:5 (2022).

© 2022. This work is licensed underneath a CC BY-NC-ND 4.0 licence.



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