If the ways for settling investment disputes surveyed in the preceding chapter prove to be unsatisfactory, what sanctions can the national state of the injured private investor take to secure conformity to the rule of respect for alien-owned property? More specifically, suppose that the investee state refuses to make adequate reparation for spoliatory measures in respect of a foreign investment, or to respond to diplomatic representations, or even refuses to submit the dispute to arbitration, and that local remedies have been exhausted in vain, what action can be taken by the national state of the private investor? This is, in the specific cases of Sudan and Saudi Arabia, perhaps a hypothetical question, because it has been the practice of successive Sudanese and Saudi governments to settle investment disputes amicably or through domestic adjudication or arbitration. Nevertheless, the question is of some importance, for it must be the background against which investment is ultimately made.

It has been contended that, if diplomatic protection yields no positive results, the state whose national's investment has suffered loss may decide to adopt unilateral measures for the enforcement of international law rules on respect for private property. Any valid unilateral action which can be taken must be in consonance with the Charter of the United Nations and customary rules of international law.