On Thursday 11 September, the Court of Justice of the European Union reaffirmed the ne bis in idem principle: a person cannot be prosecuted in one Member State for an act of terrorism for which he or she has already been convicted in another Member State, even if the legal classification is different (ruling in case C-802/23).
A leader of the terrorist organisation ETA, sentenced in France to 20 years in prison for participation in a terrorist association, is the subject of a European...