An increasing political contestation of the existing private-property order can currently be observed. With serious demands for expropriation, even outside marginalized splinter groups, a concept is returning that has largely disappeared from the focus of political theory. In this context, the article aims at a decidedly political-scientific examination of the legal institution of expropriation by locating the concept in the architecture of the democratic rule of law. Shifting between the poles of the constitutional guarantee of private property on the one hand and a potentiality of democratic contestation of the property order on the other, it is made clear that the concept of expropriation highlights the aporias of the democratic rule of law. The thesis is presented by means of a theoretical-historical contouring using the example of the intensive discussions on expropriation in the Weimar Republic and, in particular, with a more in-depth examination of the positions of Carl Schmitt and Otto Kirchheimer, which are subsequently figured as antipodes. While Schmitt seeks to make plausible a far-reaching rejection of expropriation potentials with a narrow concept of the rule of law, Kirchheimer focuses on an extensive interpretation of democratic power of disposition over the private-property order. The Weimar crisis years are examined as a kind of "laboratory" in order to profit from the extraordinary degree of crisis-induced searching and to work out a political science theoretical language for contemporary discussions of expropriation.