HASSAN v. THE UNITED KINGDOM – JUDGMENT 49 94. The International Court of Justice had provided apparently conflicting guidance on the question of the need for derogation before a State could rely on international humanitarian law. If the basis for using international humanitarian law at all was that human rights bodies should take account of other areas of international law, that might be thought to point to its use whether or not a State had derogated and whether or not it invoked international humanitarian law. On the other hand, where the State had done neither, the human rights body might wish to refer to the applicability of international humanitarian law, whilst saying that the State had chosen to be judged by the higher standard of peacetime human rights law, although such an approach might run the risk of appearing disconnected from reality. Where the State had not derogated but had relied on international humanitarian law, it would be open to the human rights body either to take account of international humanitarian law or to insist that the only way of modifying international human rights obligations was by derogation. 95. As regards the interplay between the two regimes, there could be no single applicable rule. Any given situation was likely to require elements of both bodies of law working together, but the balance and interplay would vary. Accordingly, there might be situations, such as the detention of prisoners of war, in which the combination of criteria lead to the conclusion that international humanitarian law would carry more weight, and determination of human rights violations regarding issues such as grounds and review of detention would be based on the relevant rules of international humanitarian law. Even in such contexts, however, human rights law would not be under absolute subjection to international humanitarian law. For example, if there were allegations of ill treatment, human rights law would still assist in determining issues such as the specificities of the acts which constituted a violation. From the perspective of the human rights body, it would be advantageous to use human rights law as the first step to identify the issues that needed to be addressed, for example, periodicity of review of lawfulness of detention, access to information about reasons of detention, legal assistance before the review mechanism. The second step would be to undertake a contextual analysis using both international humanitarian law and human rights law, in the light of the circumstances of the case at hand. On condition that the human rights body presented its analysis with sufficient coherence and clarity, the decisions generated would provide guidance to both States and armed forces ahead of future action. It went without saying that the approaches and the result had to be capable of being applied in practice in situations of armed conflict.