The rise of extremist political movements has fuelled the search for new mechanisms to safeguard democratic institutions. Existing mechanisms are often decried as either too legalistic (courts) or too political (parliaments). Moreover, these methods are accused of being dominated by political or technocratic elites. In addition, courts lack democratic legitimation, while parliaments pose the risk of tyranny of the majority against unpopular and vulnerable minorities. These considerations suggest the need for protective mechanisms that enjoy strong popular legitimacy, but without repeating the failings of existing democratic institutions. We suggest that randomly-selected assemblies might effectively serve as citizen tribunals enforcing anti-extremist measures. Random assemblies respect democratic equality through their selection procedures, thereby providing a strong form of democratic legitimation. They also provide descriptive representation, ensuring the politics of presence with respect to vulnerable minorities. In addition, properly-designed random assemblies can ensure impartiality; they are not bound to follow a partisan agenda and resist capture by political elites. We compare anti-extremist random assemblies with the practice of ostracism in Athenian democracy, and explore how such assemblies might operate within the European Union today.