The Crime of Aggression: Consequences of Applying International Criminal Law to a Radically Indeterminate Concept

This PhD research, started in February 2010 and completed in December 2015, concerns the reasons for applying international law, and international criminal law in particular, to the notion of aggressive war in interstate relations, and the implications of the application of (criminal) law to such an indeterminate concept. That the notion of aggression is indeterminate is demonstrated by the different conceptual frameworks and underlying assumptions that actors hold i) on the nature of international relations, ii) on the function of the use of force, and iii) on the source(s) and binding nature of international law, all of which may also vary over time and vary depending on where the conflict takes place.

In this research I found that it is highly problematic to apply international law to the notion of aggression due to the complex nature of these differing conceptual frameworks when considering the legality of a particular use of force. A humanitarian intervention, for instance, can be seen as heroism by one and supremely criminal by another. A criminal law approach requires choosing one conceptual framework over the other, a venture that scholars and politicians have not been able to agree upon since legal thinking about war started many centuries ago. To apply criminal law to such an indeterminate and inherently political notion is not only fundamentally problematic but also an overstretching of the law’s capabilities. The nature of criminal law proscribes an inherent vertical relation between the law enforcer on the one hand, acting on behalf of society (or humanity in this case?), and the criminal on the other, who has placed himself outside of the system by acting knowingly in a criminal manner. Criminal law furthermore not only presumes the existence of good and bad but also the ability to distinguish between the good and bad side. Both these aspects of the nature of criminal law are problematic when applied to the legality of war since, due to its indeterminacy, the distinction between the good and bad side can be fundamentally disagreed upon, taking away the justification required for its vertical relation.


  • Marieke de Hoon


  • Wouter Werner
  • Elies van Sliedregt

Key publications:

  • Marieke de Hoon, Collateral Damage from Criminalizing Aggression? Lawfare Through Aggression Accusations in the Nagorno Karabakh Conflict, 5 Eur. J. of Legal Studies 1 (2012), p.40-61, available at

For more information on the project contact: Marieke de Hoon

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