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).
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 line database 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)).
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.
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).