In its judgment of 3 February 2012 in Jurisdictional Immunities of the State (Germany v. Italy: Greece intervening), the International Court of Justice has examined the relationship between jus cogens and the rule of State immunity. The Court has denied the existence of a jus cogens exception to that rule, primarily on the basis of the distinction between peremptory norms as rules of substance and jurisdictional immunities as rules of procedure. For the Court, a conflict between rules on jurisdictional immunities, “essentially procedural in nature”, and substantive rules of jus cogens is conceptually impossible. This article criticizes the approach and reasoning of the Court regarding the absolute separation between procedural and substantive rules, and argues that a legal conflict may exist between jus cogens and jurisdictional immunities. Moreover, it sustains that the decision of the Court does not bring about an ideal kind of stability for the international legal order nor is it an encouraging legal message to national judges dealing with public interest claims arising from serious violations of international law.