The fact that violations of jus cogens norms occurred in the past does not entail a conflict with nor permit a state to set aside the rules of immunity. (europeanlawblog.eu)
Furthermore, US courts have recently denied foreign state officials immunity against civil claims alleging violation of jus cogens norms. (newlawjournal.co.uk)
In Samantar v Yousef (699 F. 3rd 763, 2012) the Federal Court of Appeals for the Fourth Circuit concluded that «under international and domestic law, officials from other countries are not entitled to foreign official immunity for jus cogens violations, even if the acts are performed in an official capacity». (newlawjournal.co.uk)