Cysne Case Portugal v Germany

In retaliation for a breach by Great Britain of a treaty obligation not to carry certain items as contraband, Germany added further items to the list without authority and sank a Portuguese ship that carried them. Finding against Germany the Tribunal said:

Reprisals, which constitute an act in principle contrary to the low of nations, are defensible only in so far as they were provoked by some other act likewise contrary to that law. Only reprisals taken against the provoking State are permissible. Admittedly,, it can happen that legitimate reprisals taken against an offending State may affect the nationals of an innocent State. But that would be an indirect and unintentional consequence, which, in practice, the injured State will always endeavour to avoid or to limit as far as possible