This paper provides a comparative overview of the way in which EU Member States, Genocide Network Observer States and Ukraine have implemented the crime of aggression in their domestic laws. How is the crime of aggression defined in national criminal codes? Have the majority of states adopted the definition provided by Article 8bis of the Rome Statute? Do they exercise universal jurisdiction over this crime, similar to war crimes, crimes against humanity and genocide? 

The first part of the paper briefly presents the historical evolution of the crime of aggression under international law, looking at how its main components have been shaped from the aftermath of the Second World War up until the adoption of the 2010 Kampala amendments to the Rome Statute. 

The second part of the paper provides an overview of the national criminal laws of EU Member States, Genocide Network Observer States and Ukraine and takes a look at the English translations of domestic provisions defining the crime of aggression, highlighting common features and main differences.