There is a broad political consensus that states must not facilitate money laundering, especially as relates to the proceeds of foreign grand corruption. Over the past 30 years, an elaborate regulatory regime has been put in place in most countries to ensure that proceeds of crime are interdicted and confiscated. It rests on the technically non-binding recommendations of the Financial Action Task Force, an influential intergovernmental grouping. Despite this progress and the adoption of international treaties against corruption and organized crime, international law contains no express treaty rule that enjoins states from facilitating money laundering. Furthermore, there are formidable legal and practical obstacles to invoking international legal responsibility of states that do choose to benefit from enabling money laundering. This article explores the disconnect between international law as it stands and the widely accepted political imperative that states must not facilitate money laundering. It argues in favour of recognizing a self-standing customary rule to that effect, and outlines the content and likely impact of such a rule.