Abstract This article uses the traditions of constitutionalism to develop the building blocks of a doctrine of transitional constitutional norms. After arguing that existing doctrines of implicit constitutional unamendability, such as the basic structure and constitutional replacement doctrines, are derivative, the article provides an account of the underlying primary doctrine: transnational constitutional norms. From the perspective of the form of government, constitutional norms are divided into peremptory and voluntary norms. Unearthing an old, but now largely forgotten, tradition of political thought, it defines peremptory norms as norms that derive from or constitute the form of government. These constitutional norms have a complex nature: domestic and transnational. The transnational dimension immunizes the people’s choice in favor of the democratic form of government by protecting peremptory norms from deselection, defined as the impermissible alteration or replacement of that form of government through piecemeal derogation from peremptory norms. Only the people as pouvoirconstituant, but not their representatives, may chose the form of government and only through a full-scale process of constitution-making. The article uses judicial independence to illustrate the idea of peremptory constitutional norms. The doctrine of transnational constitutional norms helps to resist attempts at undermining judicial independence and to protect the integrity of the democratic form of government against impermissible deselection.