Fair value of equal political liberties is a key precondition for the legitimacy of a regime in liberal thought. Preventing a semi-permanent lockout of a social group from all political power is a threat to the stability of liberal constitutional regimes. Given the convertibility, subtlety and resilience of power, gross material inequality—produced by neoliberal economic policies—effectively locks the relative poor (roughly, the bottom 20% of a class hierarchy) out of political power. Such lockout breaches both the legitimacy and the stability constraints of a liberal constitutional democracy. Neoliberal democracies, sooner or later, become plutocracies. This possibility should be of concern not only for liberal political theory but also for liberal constitutionalism. The usual objections to a constitutional concern with gross inequality and plutocracy—based on transparency, countermajoritarianism and flexibility—are useful design instructions, but do not rule out the constitutionalisation of egalitarian and anti-plutocratic norms. A whole panoply of legal and political constitutional measures—already familiar to or incrementally developed from liberal constitutional thought and practice—could be marshalled to promote material equality and prevent plutocracy.