Sentence:  The enumeration of situations where the <WSD>doctrine of necessity</WSD> has been invoked forms either a catalogue of serious breaches of international law or of cases susceptible of being explained without an appeal to the <WSD>doctrine of necessity</WSD>. 
Meaning of the word marked with <WSD> tags:  The principle that a state in immediate peril to its existence, from a situation not of its own doing, may in extremis be justified in violating a right of another state.