In their excellent posts on Serdar Mohammed v. Ministry of Defence  EWHC 1369 (QB), both Kubo Mačák and Marko recognise the importance and hugely impressive analysis of Mr Justice Leggatt’s judgment. We will not reiterate the coverage of the judgment. Rather, we wish to focus on one part of it, that is, the question of whether international humanitarian law (IHL) provides a legal basis for detention in non-international armed conflicts (NIACs). Whilst Kubo also focuses on this issue in his post, we will take the opposite view to him, and thus will argue that Mr Justice Leggatt correctly concluded that IHL does not contain a legal basis to detain in NIACs. To be clear, our argument is not that detention in NIACs is necessarily unlawful. The argument is simply that authorization to detain in a NIAC cannot be found in IHL, but must rest elsewhere, principally in domestic law (either of the state that detains or of the state on whose territory the detention occurs). Exceptionally, the authorization to detain may arise out of other branches of international law, in particular, it may be contained in United Nations Security Council resolutions authorizing the use of force.
It is worth spending a few moments considering why we are even asking the question whether IHL contains a legal basis for detention in NIACs. In the particular context of the Sedar Mohammed case – and other detention in armed conflict cases brought under the European human rights system – the question is relevant in considering whether Art 5 ECHR might be regarded as inapplicable in NIACs by virtue of the argument that more specific rules of IHL apply to regulate those detentions. More generally, international human rights law (IHRL) requires that any deprivation of liberty be both lawful and non-arbitrary and in the context of NIACs, it is natural to ask first whether the legal basis might be found in IHL, as it can for international armed conflicts (Arts 27(4), 42-3 and 78 GCIV; Art 21 GCIII).
In the Serdar Mohammed case, Mr Justice Leggatt provided a number of reasons for rejecting the MoD’s contention that IHL provides a sufficient legal basis for detention in the context of NIACs. We will address the key ones here. First, he considered that such a legal basis would have been made explicit in the relevant treaty provisions (common Article 3 and Additional Protocol II) had that been intended. This is a reasonable point – coercive powers should not too readily be read into applicable treaty rules without clear evidence that this is the collective intentions of the states parties.
In his post, Kubo refers to Ryan Goodman’s 2009 AJIL article, in which he notes that the logical structure of IHL is such that what is permitted in international armed conflicts should, a fortiori, be considered permitted in NIACs, for states would never have intended to restrict themselves more in the latter than in the former. However, to argue that IHL does not create a legal basis to intern in NIACs is not inconsistent with Professor Goodman’s view. IHL does not restrict states with regard to detention in NIACs anymore than it does restrict their ability to detain in IACs. States are not prohibited from detaining in NIACs, and, in that sense, are therefore permitted by IHL to detain. IHL simply does not itself provide a legal basis to do so. That legal basis must be found elsewhere. That legal basis may even provide more extensive grounds for detention than IHL would permit in IACs. So in that sense, IAC law is still more restrictive than NIAC law in this regard. However, what is significant here is that the position under IHL is independent of the subsequent development of international human rights law and any external limits that that law might impose upon the ability of states to detain in such situations (on which, see more below).
The second reason for Mr Justice Leggatt’s conclusion is that the recognition by IHL (in Common Article 3 to the Geneva Conventions and in Additional Protocol II) that detention will occur in NIACs and the regulation of the treatment of detainees in the relevant treaty provisions does not lead to an authorisation for such action. This is an eminently reasonable interpretation. There is good authority for the view that regulation of conduct by international law does not imply authorization of that conduct or acceptance of the legality of that conduct. Three examples should suffice. First, the distinction between recognition and regulation of conduct, on the one hand, and authorisation or acceptance of the legality of that conduct, on the other hand, is right at the heart of IHL as a legal regime. IHL regulates the use of force by states in armed conflict. However, IHL says nothing about the legality of that use of force under the ius ad bellum. The use of force that IHL recognises and regulates is not rendered lawful simply by virtue of the fact that it is regulated by IHL. Rather, IHL simply accepts as a fact that conflict occurs and seeks to regulate various aspects of this. Second, in international armed conflicts, Article 75 of Additional Protocol I provides fundamental guarantees even in relation to the treatment of those whose detention is not covered by the Geneva Conventions (those persons who “do not benefit from more favourable treatment” under the Conventions or the Protocol). However, the regulation of the treatment of all persons detained in connection with international armed conflicts does not thereby provide a legal basis for all detentions that occur in connection. That legal basis for detention in international conflicts is found only in the 3rd and 4th Geneva Conventions. Third, in the Armed Activities Case (Dem. Rep of Congo v. Uganda), the ICJ rejected the view that a series of ceasefire and disengagement treaties which regulated when and how Uganda was to withdraw its forces from the territory of the DRC amounted to consent to those forces being present (“in the sense of validating that presence in law”, para. 105) even during the duration of the disengagement period. The ICJ held that the agreements “took as [their] starting point the realities on the ground” and “thus represented an agreed modus operandi” for the parties (para. 99). In the same way, IHL regulation of the treatment of detainees in NIACs simply recognises the reality of detention and contains rules for that how this should occur. In so doing it does not, however, create a legal basis to detain in NIACs.
It might be argued (and Kubo in his post does argue this) that a failure to accept that IHL provides a basis for detention in NIACs would lead to a ‘paradoxical’ situation in which the law of NIACs regulates internment, whilst simultaneously internment is prohibited elsewhere by international (human rights) law. The paradox, so the argument goes, would lie in the fact that states sought under IHL to regulate internment, which they prohibit under IHRL. However, no such paradox exists. There is no general prohibition of internment under IHRL (Art 9 ICCPR, for example, merely prohibits arbitrary and unlawful detention). As long as states provide for internment in armed conflict under their domestic law, in a manner that is non-arbitrary, such detention would not a priori be prohibited by the ICCPR. Art 5 ECHR is, of course, different, in that internment, not falling within one of the permissible bases for detention listed within paragraph 1, is necessarily inconsistent with that provision. Even under the ECHR, however, states reserved for themselves the right to derogate from certain provisions, including Art 5 ECHR, in situations of war. The relevant provisions of IHL that regulate certain aspects of detention do no more than establish a baseline below which no conduct may fall in NIACs, including the conduct of non-state armed groups.
That IHL does not itself create a legal basis to detain in NIACs is to be expected. This conclusion follows from the fundamental principle that IHL applies without distinction to all parties to an armed conflict (both state and non-state alike). In extending rules to NIACs, states are keen to ensure that nothing in those rules could be read as authorising the non-state party to engage in rebellion (the travaux of common Article 3 and Additional Protocol II are full of references by the various delegates to this concern). Indeed, this was noted by Mr Justice Leggatt as another reason for finding that IHL does not provide a legal basis to intern. In his post, Kubo suggests that the principle of equal application of IHL should lead to the conclusion that non-state groups also have the right to detain in a NIAC (rather than to the conclusion that IHL provides no basis for anyone to detain in a NIAC). He suggests that states are willing to accept the former conclusion and refers to the 1991 Memorandum of Understanding in the context of the Croatian conflict as an example where states agree on specific rules to regulate detentions by non-state armed groups. Agreements between states and non-state groups which incorporate rules on detention, among other things, have become increasingly common. However, they remain ad hoc agreements concluded in the context of specific conflicts. This is a very different thing to states specifically agreeing in advance that all non-state armed groups have a legal right to detain in any NIAC. The difference is the same as that between ex post facto amnesties granted to certain non-state fighters at the conclusion of some NIACs and ex ante combatant immunity which remains restricted to lawful combatants in international armed conflicts.
A seemingly compelling argument that can be made against the view that IHL provides no legal basis to detain in NIACs, is that if IHL provides a legal basis to kill fighters in a NIAC it must also provide the lesser power to detain. Also, it may be argued that if IHL did not provide that lesser power, perverse incentives would be created as participants in an armed conflict would be better off killing than detaining (see Aurel Sari’s comment to Kubo’s post). This argument, is predicated on the assumption that IHL provides authorization or permission to kill combatants or fighters in a NIAC. In an IAC, IHL provides combatants with a right to take part in hostilities (Art. 43(2), AP I) which does imply a right to use lethal force. To be sure, IHL applicable in a NIAC provides that civilians must not be the object of an attack. However, this is not the same as saying that IHL authorises the targeting of combatants or fighters. States remain entitled to prosecute members of non-state groups for killing of members of the armed forces of the state or indeed killing members of other non-state armed groups. If IHL did indeed provide a legal basis for killing in a NIAC, it would have to do so on the basis of equality and would provide a privilege to kill (and a corresponding immunity from prosecution). It does not do this. No problem arises in practice with the view that IHL does not itself provide a basis for targeting in NIACs as this view allows the state to retain the freedom to prosecute members of the non-state group and also allows the state to provide in its own law a legal basis for its armed forces to target members of non-state groups (as long as the prohibition of attacking civilians is respected). Also, as the state is unlikely to prosecute members of its own armed forces for targeting members of the non-state group, it is not likely that problems would arise in practice even if no domestic law basis existed for such targeting. In any event, the argument that there is a perverse incentive to kill rather than to detain because human rights law would apply to the latter seems to ignore the fact that human rights law would also apply to the former (leaving aside for now questions of extraterritorial application of IHRL). In principle, both actions are subject to the restraints of human rights law.
In consequence, the legal basis for authority to detain during a NIAC lies elsewhere, primarily in municipal law and possibly in other areas of international law such as relevant Security Council resolutions authorising military action. International law allows states to adopt legislation that authorises state action deemed necessary, such as internment, whilst ensuring that non-State groups are left to be prosecuted for their ‘ordinary acts of war’ under domestic law. However, any domestic legislation thus adopted will need to comply with other applicable principles of international law, namely IHRL.
That the legal basis for detention in NIACs does not lie in IHL, whether as an implied right or a customary right, is supported by state practice. Thus, states have generally relied on domestic law as providing the legal basis for their detention practices in NIACs (see, e.g, Nepal’s infamous Terrorism and Disruptive Activities Act and Ordinance, or Sri Lanka’s Prevention of Terrorism Act). Even in the context of extraterritorial NIACs, states have looked elsewhere for authorisation (see, e.g., Iraq and Security Council Resolution 1546). If either the applicable treaty provisions or customary international law could be said to provide a legal basis for detention in NIACs, one would expect practice generally to confirm this. This does not, however, seem to be the case.