Recently, extremist ‘populist’ parties have succeeded in obtaining large enough democratic electoral mandates both to legally make substantive changes to the law and constitution and to legally eliminate avenues to challenge their control over the government. Extremists place committed liberal democrats in an awkward position as they work to legally revolutionize their constitutions and turn them into ‘illiberal democracies’. This article analyses political responses to this problem. It argues that the twin phenomena of legal revolution and illiberal democracy reveal a (...) latent tension between the constitutional commitments to democracy and liberalism, that is, the equal chance to have one’s political goals enacted into law and individual basic rights. Political extremists make the latent tension real when they use the procedures of democratic legal change to abrogate constitutional commitments to liberalism, among other things. Although the two commitments normally coexist side by side, exceptional times raise an existential dilemma for liberal democracies: is it constitutional to democratically amend liberalism out of the constitution? After analysing the moral legitimacy of both the democratic and liberal arguments, this article concludes that liberal constitutionalism is constitutive of genuine democracy. In other words, it is unconstitutional to abrogate basic liberal commitments and it is legitimate to adopt constitutional mechanisms to guarantee liberalism – even if it means constraining democracy to do so. This article then situates ‘constrained democracy’ within the liberal current as a way to conceive of and respond to this pressing problem. It concludes by discussing four constitutional mechanisms – inspired by the German Grundgesetz – to guarantee liberalism: unambiguous lexically prior commitment to liberalism, limits on negative majorities, the eternity clause and party bans. It concludes that constrained democracy is an important constitutional guarantee of liberal democracy and that the four mechanisms, among others, are essential to enact constrained democracy. (shrink)