In this article the author explores how international humanitarian law (IHL) is used in advocacy on ‘undercover’ operations—the wearing of civilian clothes by Israel's security forces in the Occupied Palestinian Territories (OPT). Assessing applicable legal standards—the duty of combatants to distinguish themselves from the civilian population, and the rule prohibiting perfidy—He shows that legal claims, reporting practices and strategies comprising the advocacy on ‘undercover’ operations in the OPT make inadequate and inefficient use of IHL. Advocacy on ‘undercover’ operations does not reference and utilize appropriate legal standards; nor does it ground allegations and strategies in the normative and factual inquiries these standards entail. Such advocacy is insensitive to highly relevant factual, legal and policy specificities of the OPT. Decontextualized, advocacy on ‘undercover’ operations presents neither a coherent legal argument nor cogent compliance-inducing strategies. It generates inefficient, unpersuasive discourse that more likely undermines than supports the prospects of changing the practices it challenges.