The experiences of multinational engagements in Kosovo in the late 1990s, and then more recently Afghanistan from 2001 and Iraq from 2003, have led to a political debate about the linkage between legality and legitimacy. At the heart of contemporary political and academic discourses about war are questions about the scope and content of the law of armed conflict. Considerably less attention has been given to another mode of regulating warfare, namely Rules of Engagement (ROE), despite their operational significance. This article seeks to begin to bridge this knowledge gap by examining ROE as a means to achieving greater legal accountability for the use of force against civilians. To that end, the article aims to do two things: first, to use examples from the US and the multinational context to develop a typology of the various issues that might affect ROE adversely in a legal accountability perspective, either as a background context or through the deployment and use of ROE itself; and second, to look at ways of rearticulating ROE, setting them on a path toward a more standardized and judicialized form of accountability.