Behavioural relevance of IL

IL is behaviourally relevant if recourse to law makes a counterfactual difference for behaviour. This means that adherence to IL has an effect on behaviour beyond what interests and non-legal normative beliefs would have led an actor to do anyway. The agent in question would have acted differently had she merely followed her normative beliefs and/or interests without considering IL.

Causal dependence of IL

In the international realm, actors create IL and comply with it if this serves their prior interests and/or accords with their extra-legal normative beliefs. IL does not provide an independent reason for action.

Containment command

When choosing targets for attack A has to engage objects and persons in B that contribute in one causal step to the competition between A’s and B’s military forces. This is deemed sufficient for this competition to proceed and for one side to achieve generic military victory.

Contingent indeterminacy

No matter how specific a legal prescription is, there are always cases for which it is unclear whether a legal rule applies. The extent of this ‘penumbra of uncertainty’ is contingent on the architecture of a legal regime and the language used. Contingent indeterminacy explains how far a rule of IL bends to endorse the interpreting actor’s prior interests or extra-legal normative beliefs.