Recent political developments around the globe demonstrate strong capacity of populist political movements to mobilise voters, gain their support and access to power. Public law should remain on guard to protect democracy from its potential enemies. This paper argues militant democracy is an inherent quality of democracy and offers valuable theoretical and practical tool to address this new challenge to democracies and their existence. The paper analyses the role of public international law and international organisations to argue there are strong signs public international law favours a substantive view of democracy and moves towards considering states as having an obligation to preserve and guard democracy and its institutions from attacks within. Public international law grants capacity to international organisations to exercise militant democracy measures in relation to Member States that disrespect and ignore major democratic principles and rules.