This volume offers an up-to-date overview of the much-debated issue of how a democracy may defend itself against those who want to subvert it. The justifications, effectiveness and legal implications of militant democracy are discussed by addressing questions as: How can militant democracy measures such as party bans be justified? Why is it that some democracies ban antidemocratic parties? Does militant democracy succeed in combatting right-wing extremism? And is militant democracy evolving into an internationalized legal and political concept? Bringing together experts and perspectives from political science, law and philosophy, this volume advances our understanding of the current threats to democracy, a political system once thought almost invincible. It is especially timely in the light of the rise of illiberal democracy in the EU, the increasingly authoritarian rule in Turkey, the steady shift to autocracy in Russia and the remarkable election of Trump in the US.