Expulsion of aliens is a matter of domestic law in which States enjoy a broad discretionary power (Hailbronner and Gogolin in Aliens, Max Planck encyclopaedia of public international law. Oxford University Press, Oxford, 2015, Murphy in Am J Int Law 107:164–194, 2013). European law and institutions leave a broad margin of appreciation in that field to the Member States. In addition to the expulsion of illegal aliens, national authorities may, on the grounds of public policy and public security, revoke a legal resident’s residence permit and expel him or her, regardless of his or her level of integration within the host country. The Belgian legislature recently extended the scope of expulsion measures to all legal residents. The chapter analyses the evolution of expulsion measures highlighting the limits set by the European legal framework and questioning their underlying logic.