Intertemporal law governs the applicability of international legal norms ratione temporis. According to often used terminology, intertemporal law has two different branches. This article provides clarification of the so-called ‘second branch of intertemporal law’. It does so by refuting two commonly held assumptions. First, as established in section 2 of the article, the second branch of intertemporal law is not an exception to the first branch of that law. It cannot be, since both branches of intertemporal law centre on the same legal principle: an action or a factual state of affairs must be assessed in the light of the law which is contemporary with it. Secondly, as implicated by the line of reasoning in section 2, and further confirmed by the inferential evidence cited in section 3, the practical relevance of the second branch of intertemporal law is not confined to the application of the law on the acquisition to territory. It pertains to a more widely defined group of norms in international law.

This article explores the implications for the protection of civilians and other vulnerable persons, of the requalification of a conflict downwards from international to non-international, focusing in particular on the changes in the characterization of the conflicts in Afghanistan and Iraq from 2001 and 2003 respectively.

Determining the legal character of an armed conflict is rooted in an inherently political interpretation of black letter treaty law. It is generally agreed that when the United States and its coalition allies entered the wars in Afghanistan in 2001, and Iraq in 2003, their operations in those countries were initially subject to the laws of international armed conflict. However the International Committee of the Red Cross (ICRC) has determined that the conflict in Afghanistan became non-international with the establishment of the United States' backed government of Hamid Karzai on 19 June 2002 and that the conflict in Iraq became non-international with the establishment of the Iraqi Interim Government on 28 June 2004. The basis for this requalification is Article 2 of the Geneva Conventions read in conjunction with an interpretation of the meaning of ‘state’ (and of its power to authorize a foreign intervention in its own territory) that is inherently, and possibly inevitably, political.

Changes in the legal characterization of a war have profound implications for the protection of both non-combatants and combatants under international humanitarian law, in particular for humanitarian access; for the protection of non-nationals from deportation; for the protection of detainees; for the conduct of hostilities; and for the protection of persons transferred into the hands of local authorities. The practical consequence of a requalification of an armed conflict downwards to non-international is a marked loss of protection for persons that were protected by the Geneva Conventions in the earlier stages of the conflict.

In this article I discuss the legality of Israel's interception of the Mavi Marmara on May 31 2010. Although Israel's stopping, boarding and inspection of the Mavi whilst on the high seas would undoubtedly constitute a violation of the law of the sea during peace time, I examine whether this violation can be justified on the basis of international humanitarian law. Specifically, Israel asserts that it was enforcing a naval blockade. I examine the legality of this blockade. I suggest that the blockade was unlawful on the basis that customary international humanitarian law permits the use of naval blockades only in times of an international armed conflict. I argue that on May 31 2010 Israel was not engaged in an international armed conflict with Hamas. Moreover, I submit that customary international law prohibits the use of blockades where they are intended to deny the civilian population objects essential for its survival or where the damage to the civilian population is excessive in relation to the anticipated military advantage. Israel argues that the intention of the blockade was to prevent war material from being delivered to Hamas fighters. This notwithstanding, I argue that because this blockade was causing a severe humanitarian crisis in Gaza on May 31 2010, it was incompatible with customary international law and therefore unlawful. Furthermore, even if the deployment of the blockade could be considered lawful, I argue that the enforcement of the blockade was unlawful because Israel's use of force to capture the vessel went beyond what was necessary in the circumstances.