This short essay explores the importance of fear and violence in the genesis and life of constitutions, with a particular focus on the case of secession. Secession has been seen as a taboo and until recently constitutions tried to avoid mentioning it, considering such a phenomenon as an extra legal fact. A turning point has been represented by the famous Reference of the Canadian Supreme Court on Québec. Finally, in the last part of this work I shall try to present (...) some arguments in favour of the explicit constitutionalization of a secession clause in multi-national federalisms. (shrink)