What are derogations to human rights treaties?

States have a right to derogate from certain obligations in order to deal with public emergencies. When a state finds itself in a state of emergency, some civil-political human rights may be temporarily restricted (“derogation”, Article 4, ICCPR). However, a state of emergency always has to be officially declared and accounted for, and has to be limited in time. Some human rights like the prohibition of torture cannot be derogated under any circumstances. All other human rights treaties do not allow the temporary derogation of particular rights in a state of emergency.