Define article 22 ARSIWA (lawful countermeasures).

A state must be allowed to respond to another state's international wrongful acts by taking certain countermeasures in order to bring the wrongful acts to an end. There are requirements: 1. Art. 49: only against the other state and with purpose to resolve the matters 2. Art. 50: there is a fine line you can't cross (article 2(4) UN Charter, etc.) 3. Art. 51: proportionality 4. Art. 52: procedural requirements 5. Art. 53: countermeasures must be terminated as soon as the wrongful act ceased.