This article investigates how – by breaking with the historical double standards regarding civilian protection in conflicts – by the end of the twentieth century, US warfare has come to comply with International Humanitarian Law (IHL). Yet, civilians are still being killed. This has sparked controversies over what constitutes legitimate targeting practices and as to whether higher levels of civilian protection could be achieved. Through an engagement with these debates, including an exploration of the evolution of the norm of non-combatant immunity with specific reference to US warfare, the article argues that IHL does not provide fully satisfactory answers to these issues as it is too permissive in relation to the killing of civilians. The article proposes that more stringent moral guidelines, such as those underpinning the idea of ‘due care’, have the potential to go much further in providing protection for the innocent in war.