In 2005, the International Committee of the Red Cross (ICRC) completed a ten-year study on customary international humanitarian law, based on an assessment of the State practice of over 150 nations over the preceding thirty years. Somewhat surprisingly, but perhaps owing to the sheer size of the ICRC Study, only two states have officially responded to the ICRC: the United States and Israel. Although an analysis of the US response is beyond the scope of this paper, it generally criticizes the ICRC Study's unorthodox methodology, including both the State practice it considered, and its lack of proof of opinio juris.

The ICRC is a venerable organization, traditionally viewed as the guardian of international humanitarian law. Its study is a monumental work compiling a surfeit of State practice. Nevertheless, the ICRC Study articulates ‘rules’ that are not sustainable under the traditional theory of customary international law formation, as may be seen by the examination in Section 3 of the three seemingly uncontroversial rules proposed for handling the wounded, sick and shipwrecked.