 An injury to an alien is considered to be an indirect injury to his home country and in taking up his case the state is seen as asserting its own rights.This means that a state is in no way obliged to take up its national's case and resort to diplomatic protection if it considers this not to be in its own political or economic interests.Customary international law recognises the existence of certain requirements that must be met before a state can validly espouse its national's interest.