Responding to Ryan Goodman About Serdar Mohammed — Part I

Responding to Ryan Goodman About Serdar Mohammed — Part I

At Just Security, my friend Ryan Goodman has posted a long analysis of Serdar Mohammed v. Ministry of Defense, in which the UK High Court held that IHL neither authorizes nor regulates detention in non-international armed conflict (NIAC). That decision will soon be considered by the Court of Appeal.

In his post, which is a must-read, Ryan states that he agrees with the High Court that IHL does not authorize detention in NIAC but disagrees that IHL does not regulate such detention. I share Ryan’s position on the first point, but I disagree with him — and agree with Justice Leggatt in Serdar Mohammed — on the second. In a subsequent post, I will address Ryan’s argument that “whatever is permitted in international armed conflict is permitted in noninternational armed conflict.” I have described that argument in a forthcoming book chapter as “reasoning by analogy”; Ryan rejects that description and says he is engaging in “reasoning by structure.” I will try to show in the next post that the “whatever is permitted” argument is problematic no matter how we describe its underlying reasoning.

In this post, I want to focus Ryan’s argument that, contrary to Justice Leggatt, IHL does in fact regulate the permissible grounds for detention in NIAC. Here is what he says (emphasis mine):

So far we have discussed the permissive boundaries of detention in NIAC but what about limitations on states in these contexts? IHL also imposes a set of prohibitions on the grounds for detention in internal armed conflict. That is, multiple sources conclude that IHL prohibits arbitrary deprivation of liberty in NIAC (see footnote 12 of the AJIL article, for example). Subsequent to that law review article, several important states through the Copenhagen Process—including “specially affected” states which is a significant category for customary international law purposes—explicitly accepted such restrictions on detention in NIAC.  Consider also the ICRC’s statement in a Background Paper on detention for the regional consultations 2012-2013: “In terms of grounds for internment, the ICRC, along with a growing international consensus of experts considers that ‘imperative reasons of security’ is an appropriate standard for internment in NIAC.” And a Report by a group of experts convened by the ICRC and Chatham House “quite easily” reached a consensus that in NIACs “parties to a conflict may capture persons deemed to pose a serious security threat and that such persons may be interned as long as they continue to pose a threat.” (See also the ICRC’s customary international humanitarian law Rule 99: Deprivation of Liberty).

To begin, it’s worth noting that Ryan does not seem to be “reasoning by structure” here — he seems to be arguing that, as a matter of customary international law, IHL prohibits arbitrary detention in NIAC. After all, he specifically mentions custom and “specially affected” states in the context of the Copenhagen Process. Moreover, he refers to the ICTY’s jurisdiction decision in Tadic both here and in his superb law-review article on security detention — and Tadic specifically based its (methodologically dubious) extension of IAC-based rules of IHL to NIAC on customary international law. As it said with regard to those rules (para. 127), “it cannot be denied that customary rules have developed to govern internal strife.”

If Ryan is claiming that IHL prohibits arbitrary detention in NIAC as a matter of customary international law, I have no theoretical objection to his argument. Indeed, as I’ll explain in my next post, my position is that international human rights law (IHRL) governs the regulation of detention in NIAC precisely because there are no contrary customary rules of IHL that can serve as the lex specialis of detention. If there are such customary rules, IHL may well displace IHRL (depending on how we understand the lex specialis principle).

That said, I take issue with Ryan’s claim that (as a matter of custom?) IHL prohibits arbitrary detention in NIAC — a standard that has no basis in the conventional IHL of NIAC and is normally associated with IHRL. He begins his post with the Copenhagen Process, which resulted in a list of principles governing detention in NIAC. The problem with relying on those principles is that they are lex ferenda — policy prescriptions — not lex lata. The Commentary to Principle 16 makes indisputably clear that the state participants did not believe the principles reflected customary international law and did not intend the principles to serve as opinio juris for the creation of new customary rules (emphasis mine):

16.2. This savings clause also recognises that The Copenhagen Process Principles and Guidelines is not a text of a legally binding nature and thus, does not create new obligations or commitments. Furthermore, The Copenhagen Process Principles and Guidelines cannot constitute a legal basis for detention. Although some language, e.g., Principle 2, may reflect legal obligations in customary and treaty law, The Copenhagen Process Principles and Guidelines are intended to reflect generally accepted standards. In such instances, the applicability and binding nature of those obligations is established by treaty law or customary international law, as applicable, and not by The Copenhagen Process Principles and Guidelines. Since The Copenhagen Process Principles and Guidelines were not written as a restatement of customary international law, the mere inclusion of a practice in The Copenhagen Process Principles and Guidelines should not be taken as evidence that States regard the practice as required out of a sense of legal obligation.

A different problem affects Ryan’s second source, the ICRC Background Paper. The Paper does indeed say that “the ICRC, along with a growing international consensus of experts considers that ‘imperative reasons of security’ is an appropriate standard for internment in NIAC.” But it does not say that the “imperative reasons” standard comes from IHL — or at least not solely from IHL. Instead it says this (p. 14; emphasis mine):

These safeguards draw on the principles and rules applicable in international armed conflict, on customary IHL, and on human rights law. While certain of them, in the view of the ICRC, are obligatory in order to prevent arbitrariness in decisions to intern, they are not clearly expressed in any IHL treaty applicable to NIAC.

This is not particularly helpful from a legal standpoint, because it does not tell us which principles and rules are obligatory, not simply desirable, and does not tell us whether the obligations that do exist come from IHL, from IHRL, or from some interplay of the two. What is clear, though, is that the ICRC does not believe the general prohibition on arbitrary detention in NIAC comes from IHL. As it says (p. 12):

Common Article 3 makes no explicit mention of internment, let alone the appropriate grounds and procedures for such a regime. AP II, for its limited part, refers to both criminal detention and internment but only contains detailed provisions for the former. Like Common Article 3, AP II says nothing of the acceptable grounds or required procedural safeguards for internment. Insofar as customary law might be concerned, State practice has not supported the existence of any detailed rules to protect against arbitrary internment.

The same uncertainty undermines Ryan’s reliance on the ICRC’s study of customary international law. It is true that Rule 99 explicitly provides that “arbitrary deprivation of liberty” is prohibited in both IAC and NIAC. But it does not derive that prohibition exclusively from IHL. The very first sentence of the section on NIAC states that “[t]he prohibition of arbitrary deprivation of liberty in non-international armed conflicts is established by State practice in the form of military manuals, national legislation and official statements, as well as on the basis of international human rights law” (emphasis mine). It then goes on to cite the prohibitions on arbitrary deprivation of liberty in the ICCPR, the Convention on the Rights of the Child, the European and African human-rights conventions, and General Comments by the HRC. Moreover, with the exception of a passing reference to the Fourth Geneva Convention, the ICRC’s entire discussion of the “procedural requirements” governing detention in NIAC is based exclusively on IHRL. If anything, then, the ICRC seems to view detention in NIAC as regulated largely by IHRL, not by IHL.

Finally, there is Ryan’s reference to the Report that emerged from an expert meeting convened by the ICRC and Chatham House. Of all the sources he cites, the Report comes the closest to supporting his position; as he notes, the experts “quite easily” concluded (pp. 3-4) that “[t]he definition of arbitrary deprivation of liberty in the context of an armed conflict is to be considered through the prism of IHL based on the lex specialis principle that governs the relationship between the two bodies of law.” The problem for Ryan is that the experts went well beyond affirming that IHL regulates detention in NIAC. On the contrary, they also “quite easily” concluded that IHL authorizes detention in NIAC — a position that Ryan explicitly rejects. As they said (p. 3; emphasis mine):

The first question addressed was whether parties to a NIAC have the right to intern individuals to start with. During the meeting, consensus was reached quite easily about two parts of the answer to that question. On the one hand, the experts agreed that there was not so much a “right” but rather an “authorization” inherent in IHL to intern persons in NIAC. It was suggested to speak of the “power to intern” or of a “qualified or conditional right to intern” rather than of a “right to intern”. This was held to be consistent with both the spirit of IHL and from an IHRL perspective.

Ryan may well reject the experts’ position on authorization but accept their position on regulation. But if so, he should explain why they are (methodologically) wrong regarding the former but (methodologically) right regarding the latter.

In sum, the sources that Ryan cites provide almost no support for the idea that IHL itself prohibits arbitrary detention in NIAC. Insofar as that is the correct standard — and I argue that it is in my chapter — the prohibition would seem to be based on IHRL, not IHL, via the lex specialis principle.

So we end where we began: with Ryan’s argument that he is “reasoning by structure” and not “reasoning by analogy” when he derives from IAC the principles governing the regulation of detention in NIAC. If IHL does not prohibit arbitrary detention in NIAC as a matter of conventional or customary law, that standard must apply “by structure.” I will address that argument in my next post.

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Surely common Art. 3 and Protocol II prohibit “hostage”-type detentions, detentions that are “cruel” or “inhuman.” Where or not these are considered direct or indirect, they are limitations with respect to detention as well as independent proscriptions.


Further, common Article 3 clearly contemplates detention: “Persons taking no active part in hostilities, including … those placed hors de combat by … detention.”
What would be relevant with respect to whether or not there is an implied recognition of the propriety of detention under VCLT art. 31(3)(c) would involve inquiry whether or not there is a general practice of detention and whether there are supportive general patterns of legal expectation (opinio juris).
Back to treaty interpretation.

Tamás Hoffmann

I think that Tadic should definitely not be accepted as custom in its entirety. In an earlier article I tried to prove that it was essentially an attempt by Judge Antonio Cassese to initiate the creation of a body of customary law of non-international armed conflict.

To the extent that Tadic was accepted by states, e.g. with respect to individual criminal responsibility or the criminality of perfidy non-international armed conflicts it has indeed been very succesful. In other respects – and I would include the question of detention in NIAC – there is indeed much doubt whether there really is a customary regulation.

Aurel Sari

Kevin, “reasoning by structure” actually leads to the conclusion that LOAC does provide a legal basis for status-based detention in NIAC. At least that’s the argument we make in an article just published in International Law Studies (

Aurel Sari

Kevin, I’m not convinced of your reading of the relationship between custom and the Copenhagen Principles. Yes, the commentary makes clear that the Principles are meant to be neither a codification of existing custom nor to count as opinio juris. But that does not prevent them from reflecting (as in ‘coinciding with’) customary international law. In fact, the commentary itself says so. The more important ‘structural’ (in Ryan’s sense) point is that the participating States can hardly be presumed to have participated in an exercise which is (a) completely futile because it adds nothing to existing IHRL requirements on detention or (b) regulates detention practices which the participating States consider to be incompatible with IHRL. Put differently, the existence of the Copenhagen Principles confirms that the participating States recognise the tension between IHRL and IHL and that this tension is not to be resolved automatically in favour of IHRL.

Aurel Sari

Sorry if I wasn’t clear. There are three points to my argument. First, we agree that the Copenhagen Principles cannot be read as a restatement of custom or as opinio juris for detention in NIAC. We must look elsewhere for an authority to detain. Second, this does not exclude the possibility, however, that the Copenhagen Principles may reflect rules of custom. Third, the existence of the Copenhagen Principles confirms that a legal authority to detain beyond the confines of IHRL does exist somewhere. Otherwise the Principles would be futile. What all this means is that the Copenhagen Principles are not simply neutral. They presuppose the existence of an authority to detain beyond IHRL and thereby confirm that authority.

Ezequiel Heffes

Thank you Kevin for these interesting posts.

Do you consider IHRL as binding towards armed opposition groups? Because, if it is not, then there would be a gap between the international obligations of States and these entities with regard to the legal basis of detentions in NIACs in terms of “arbitrary detentions”. Those detainees by States would simply have more “protections” than those of armed opposition groups. As I explain here, among other arguments, ( If IHL would be the applicable framework, both parties to the conflict could have the same international obligations before individuals who are detained.

Ezequiel Heffes


Your latest post raises quite interesting issues, and I agree that the Opinion Paper is not as straight forward as it could be. However, I don’t see the ICRC affirming that in traditional one-State NIACs IHL does not authorize detentions. It actually affirms that this framework could also be used as a legal basis but a “careful examination of the interplay between national law and the applicable international legal regimes will be necessary”.

Moreover, there is nothing to conclude that this could not imply the application of an “inherent” power to intern given by IHL, which I don’t believe the ICRC is framing only to extraterritorial NIACs. This is mainly because of this phrase, and having in mind that AP II is not applicable extraterritorially: “This position is based on the fact that internment is a form of deprivation of liberty which is a common occurrence in armed conflict, not prohibited by Common Article 3, and that Additional Protocol II – which has been ratified by 167 States – refers explicitly to internment.”

Ezequiel Heffes


Thank you for your comments and questions. I have no certainty on why it makes such a distinction. Some issues can be raised though.

Firstly, it doesn’t say “informed by IHL and IHRL”. It says, and I believe it’s not a coincidence, “domestic law, informed by IHRL, and IHL”, which could be seen as also placing IHL as a legal basis for detention in traditional NIACs.

Moreover, even if it is affirmed in the section on extraterritorial NIACs, the ICRC seems to include all kind of NIACs. It says “both customary and treaty IHL contain an inherent power to intern and may in this respect be said to provide a legal basis for internment in NIAC”. Don’t you think that otherwise it would have said “…a legal basis for internment in extraterritorial NIAC”?


[…] of NIACs. As I set out here and here (and as also has been highlighted by Lawrence and Dapo, Kevin and Jonathan, and in published form by Els and Gabor) the development of the law of NIAC shows that […]