Shortly after Russia’s invasion of Ukraine, several nations, led by Canada and Ukraine, suspended the application of the World Trade Organization’s Most Favoured Nation (MFN) treatment to Russian goods. MFN is a foundational principle of WTO law, contained in Article I of the General Agreement on Tariffs and Trade (GATT). It promises that all WTO members will receive the same treatment as each other – the lowest tariffs on all goods offered by each WTO member will be made available to all. The effect of this trade sanction against Russia will not be lost on its president – Vladimir Putin’s masters’ thesis was allegedly on the importance of the MFN principle to international trade. The actual impact of the revocation of MFN on Russia may be less significant and the legal issues behind it are complex and troubling.