RetorsionRetorsion (French rétorsion, from Latin retortus (influenced by Late Latin, 1585–95, torsi, a twisting, wringing), a phrase used in International Law

International law

Public international law concerns the structure and conduct of sovereign states; analogous entities, such as the Holy See; and intergovernmental organizations. To a lesser degree, international law also may affect multinational corporations and individuals, an impact increasingly evolving beyond...

 is an act perpetrated by one nation upon another in retaliation or reprisal for a similar act perpetrated by the other nation. The typical methods of retorsion are the use of comparably severe measures against citizens of the foreign nation found within the borders of the retaliating nation. It is different from a reprisal

Reprisal

In international law, a reprisal is a limited and deliberate violation of international law to punish another sovereign state that has already broken them. Reprisals in the laws of war are extremely limited, as they commonly breached the rights of civilians, an action outlawed by the Geneva...

in that the retorsion is always an action in conformity with international law, though unmistakably an unfriendly one. Examples include international trade, where disputes within the WTO are typically tackled in this manner, if dispute settlement does not reach its goal.

Retorsion signifies also the act by which an individual returns to his adversary evil for evil.