The UK Court of Appeal in Serdar Mohammed: Treaty and Customary IHL Provides No Authority for Detention in Non-international Armed Conflicts

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Last week’s judgment in Mohammed v. Secretary of State for Defence is rich in analyses and observations concerning detention in non-international armed conflicts (NIACs). One of the key issues assessed concerns the power to detain in NIACs under IHL.

The Secretary of State’s position on this point commenced with a challenge to traditional classifications of armed conflict, contrasting purely internal conflicts with armed conflicts between two States (para 168). It was contended that the legal position concerning the authority to detain in a NIAC now reflects a more complex factual position than that captured under traditional classifications. A third classification must now be recognized: ‘internationalised’ NIACs. This echoes the ICRC’s Opinion Paper on internment, which speaks of ‘NIACs with an extraterritorial element’, in which “the armed forces of one or more State, or of an international or regional organization, fight alongside the armed forces of a host State, in its territory, against one or more organized non-State armed groups” (page 7).

To paraphrase, ‘if it looks and feels like an international armed conflict, let us apply IHL rules on international armed conflicts by analogy’. This is a dangerous approach that the Court of Appeal carefully avoided, instead focusing on its proposed implications.

Absence of prohibition

A preliminary question before the Court of Appeal was whether IHL allows for non-arbitrary deprivation of liberty, by virtue of the fact that Rule 99 of the ICRC’s catalogue of rules of customary IHL positively prohibits arbitrary detention, but does not expressly prohibit non-arbitrary detention. The Court ultimately accepted, however, that modern international law is such that an approach under which ‘absence of prohibition equals authority’ is outdated and cannot stand as a proper basis of authority for detention (para 197). The Court was right. No credible lawyer could genuinely assert that lack of an express prohibition constitutes authority to deprive persons of their liberty.

Authority to detain derived from customary international law

On this point, it was argued that States involved in internationalised NIACs do detain persons, and have done so for many years on the understanding that they can as of right (para 222). In other words, a customary norm of IHL has developed in the context of this third category of conflict. The Court of Appeal disagreed, concluding that: “…we do not consider that in the present state of the development of international humanitarian law it is possible to base authority to detain in a non-international armed conflict on customary international law” (para 242). The Court is correct, of course, although it left the door open for the possibility that such a custom might crystalise in time.

Authority to detain derived from Common Article 3 and Additional Protocol II

The central focus of this post is on the Secretary of State’s proposition that authority to detain in a NIAC can be derived from IHL treaty law. Relying on Common Article 3 and Articles 5 and 6 of Protocol II, the Secretary of State argued that these provisions imply an authority to detain in NIACs. Support was taken from Gill’s and Fleck’s proposal (see para 240) that although IHL treaty law concerning NIACs is less explicit in stipulating the legal basis for operational detention than IHL treaty law concerning IACs:

“…a generic power to that effect is implicit in Common Article 3, in as much as it identifies as one category of persons taking no active part in hostilities ‘those placed hors de combat by… detention’. Articles 5 and 6 of (Protocol II) also refer to ‘persons deprived of their liberty for reasons related to the armed conflict, whether they are interned or detained’, which makes it clear that the deprivation of physical liberty of a person is contemplated in the law applicable to non-international armed conflicts.”

This approach forms the basis of the ICRC’s assertion that Common Article 3 and Protocol II govern deprivation of liberty in NIAC (page 6). Because Protocol II – which relates exclusively to NIACs – explicitly mentions internment, the ICRC expresses the view that this confirms that internment “is a form of deprivation of liberty inherent to NIAC” (page 7).

The Court of Appeal nevertheless concluded that “it is not possible to base any implication of a power to detain in an internationalised non-international armed conflict purely on a treaty” (para 219). The Court of Appeal most certainly got it right, for various reasons.

  1. If the Geneva Conventions and their Additional Protocols had intended to provide a power to detain in a NIAC, this would have been expressly provided

Normal principles of interpretation require that, where certain matters have been explicitly set out in a legal instrument, the lack of similar explicit reference elsewhere in the legal instrument calls for interpretation that such matters are excluded (the principle of expressio unius). It is therefore relevant to contrast the way in which the authority to detain is dealt with in the context of international versus non-international armed conflicts.

The authority to detain in an IAC is set out in great detail within IHL treaty law. Specific authorisation and substantive grounds are specified in Article 21 of Geneva Convention III (concerning POWs) and Articles 42 and 78 of Geneva Convention IV (concerning civilians posing a serious threat to security). In contrast, the Geneva Conventions and their Additional Protocols are silent concerning grounds or procedures for internment in the context of a NIAC.

In the High Court, Mr Justice Leggatt therefore stated that: “I think it reasonable to assume that if CA3 and/or AP2 had been intended to provide a power to detain they would have done so expressly – in the same way as, for example, Article 21 of the Third Geneva Convention provides a power to intern prisoners of war. It is not readily to be supposed that the parties to an international convention have agreed to establish a power to deprive people of their liberty indirectly by implication and without saying so in terms” (para 242). This conclusion is intimately linked to the question of why IHL treaty law omitted explicit authority to detain in NIACs, influential for the Court of Appeal and considered next.

  1. It is highly plausible that the negotiating States to the Geneva Convention did not want to authorise grounds for detention in NIACs

It is not genuinely conceivable that the parties negotiating the Geneva Conventions should have been so specific in the drafting of Geneva Conventions III and IV concerning detention in the context of IACs and then leave an only vaguely implied authorisation in the context of NIACs.

In fact, there are cogent reasons why negotiating States would not have wanted to establish a legal authority to detain persons in non-international armed conflicts. Given that Common Article 3 applies to “each Party to the conflict”, and that Protocol II applies to non-State armed groups that are able to implement Protocol II, Justice Leggatt focussed on one of the cornerstones of IHL: reciprocity. He observed that: “…providing a power to detain would have meant authorising detention by dissident and rebel armed groups. That would be anathema to most states which face a non-international armed conflict on their territory and do not wish to confer any legitimacy on rebels and insurgents or accept that such groups have any right to exercise a function which is a core aspect of state sovereignty” (para 245). The Court of Appeal thus gave weight to the fact that “the original ICRC draft of the Geneva Conventions which provided for the application of the Conventions in their entirety to non-international armed conflicts was rejected” by the negotiating States (para 178).

  1. If Common Article 3 and Protocol II were to be interpreted as implying an authority to detain in NIACs, it would be necessary (but it is not possible) to identify the scope of such an implied power

As noted, IHL prohibits arbitrary detention. The commentary to Rule 99 explains that State practice establishes this rule as a norm of customary international law applicable in both international and non-international armed conflicts, noting also that the arbitrary deprivation of liberty is incompatible with the requirement that detainees be treated humanely, reflected in Common Article 3.

Common Article 3 and Rule 99 in this respect reinforce the general prohibition against arbitrary detention. This prohibition is reflected in Article 9(1) of the ICCPR, which provides that “no one shall be subjected to arbitrary arrest or detention” and requires that any deprivation of liberty be “on such grounds and in accordance with such procedure as are established by law”. These phrases echo the prohibitions against arbitrary deprivation of liberty on the one hand and unlawful deprivation of liberty on the other.

Two requirements arise from this. The first, as confirmed in the Human Rights Committee’s General Comment on the right to liberty (para 11), is that any detention that lacks a legal basis is both unlawful and arbitrary, and thus in violation of both aspects of the prohibition. The second is that the law must be defined “with sufficient precision to avoid overly broad or arbitrary interpretation or application” (para 22). If a person is detained without such legal authorization, the deprivation of liberty is unlawful and thereby in violation of Article 9(1).

From this second requirement, it follows that the law must identify the scope of any express or implied authority to detain. The Geneva Conventions and their Additional Protocols do not point to the scope of any power to intern in NIACs. Indeed, the ICRC’s catalogue of rules of customary IHL points to no express or implied authority to detain in the context of NIACs. It instead recognises that: “The 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”. There is no assertion, or even vague suggestion, that Common Article 3 and/or Protocol II imply a legal authority to detain.

Justice Leggatt was therefore correct to take the view that it is not possible to deduce the scope of any implied power from the Conventions or their Protocols (para 246), with the Court of Appeal concluding that this fact could not be overcome (paras 217-218).

  1. Because the scope of any implied power to intern in NIACs is not discernible, such internment would be arbitrary

 General Comment 35 of the Human Rights Committee states (at para 64) that: “Security detention authorised and regulated by and complying with international humanitarian law in principle is not arbitrary” (emphasis added). The non-arbitrary nature of detention in armed conflict is thereby predicated as detention that satisfies the following cumulative elements: (i) it is authorized by IHL; (ii) it is regulated by IHL; and (iii) it is thereby capable of being evaluated as to its compliance with IHL.

Even if the argument of an implied authority under Common Article 3 and Protocol II were to be accepted (element (i)), the argument fails elements (ii) and (iii) of the Human Rights Committee’s test. Geneva Conventions III and IV specify who in an IAC may be detained, on what grounds, in accordance with what procedures and for how long. In the context of a NIAC, however, it is not possible to point to any such regulation, thus falling short of element (ii). The lack of such regulation not only fails element (ii), it also makes it impossible to ascertain whether any detention in a NIAC complies with IHL (element (iii)).

General Comment 35 also distinguishes between international versus non-international armed conflicts as this concerns any derogation from the right to liberty. In the context of an IAC, it acknowledges that IHL includes substantive and procedural rules that help to mitigate the risk of arbitrary detention. Outside that context, however, the Committee spoke of the need for derogating measures (para 66). It is implicit that the Committee did not consider that IHL rules pertaining to detention in a NIAC provide sufficient procedural guarantees mitigating the risk of arbitrary detention.

  1. IHL contemplates internment as a form of deprivation of liberty in NIACs, but only as a matter of fact, not as a matter of law

While Common Article 3 and Protocol II may contemplate that the detention of persons in a NIAC may take place as a matter of fact, it does not follow that these provisions imply a lawful authority for detention. As simply put by the Court of Appeal: “Regulation is not the same as authorisation” (para 180).

  1. The purpose of Common Article 3 and Articles 5 and 6 of Protocol II is simply to guarantee a minimum level of humanitarian treatment

Common Article 3 and Protocol II require that any detained persons be treated humanely (Common Article 3), that they enjoy certain generally applicable rights and safeguards (such as the benefit of medical examinations: Protocol II, Article 5(2)(d)) and that they enjoy certain procedural safeguards pertaining to prosecution and punishment (Protocol II, Article 6). As noted in the ICRC Commentary on the Additional Protocols (at para 4440): “Like common Article 3, Protocol II has a purely humanitarian purpose and is aimed at securing fundamental guarantees for individuals in all circumstances” (emphasis added).

Justice Leggatt thus remarked: “The need to observe such minimum standards is equally relevant to all people who are in fact detained, and does not depend on whether or not their detention in legally justified” (para 244). The Court of Appeal agreed (para 218). In short, the central basis for the Secretary of State’s argument was fundamentally flawed: the provisions relied on do not imply an authority to detain; their purpose is to guarantee minimum levels of humanitarian treatment.

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