It is generally recognised in both literature and jurisprudence that the notion of proportionality constitutes a key requirement of self-defence and of countermeasures. The determination of the exact content of the proportionality principle is, however, very complex and controversial. In both areas questions such as ‘proportionate to what?’ or ‘what role does the objective of the response play?’ arise. Elucidation of the scope of proportionality in the two spheres in which it is most contentious is thus sought. Ever since the abandonment of former Draft Article 19 the term ‘State crime’ no longer exists. This study demonstrates that consequently a State can no longer commit an international crime. Yet it also shows that by applying more serious consequences to the commission of a serious breach of peremptory norms the idea behind the concept does add something valuable to the existing concepts of jus cogens and obligations erga omnes.