A state can protect its nationals who suffer injury in consequence of a breach of international law by another state. Diplomatic protection means that the state intervenes on its own account to the benefit of the injured party. Because of the strict conditions attaching to diplomatic protection, however, it is quite unusual in practice. Consular protection is the more common way for a state to intervene to the benefit of its citizens.

The state is entirely free to extend diplomatic protection or refuse it. International law places the state under no obligation to extend diplomatic protection to its nationals, and nor does any provision on Swiss law confer any such right on the individual. The sole restriction on the Federation’s discretionary powers is the prohibition of the arbitrary use of power. However, a recent decision of the Federal Court appears to find that the refusal of diplomatic protection can, in fact, be disputed (see  Federal Court decision 130 I 312, p. 317f. in French). The Federal Council is the competent authority to grant diplomatic protection.

The state cannot extend diplomatic protection unless the following 3 preconditions are met:

• nationality of the injured party
• breach of international law by the receiving state
• exhaustion of means of legal redress within the state

The state can extend diplomatic protection only to its own nationals. It is important that there should be absolutely no doubt about the nationality of the injured party. Such nationality must also be enduring: the person concerned must have it at the time of the injurious event as well as when the complaint is lodged.

Multiple nationality can raise problems with diplomatic protection. A state can on principle not exercise diplomatic protection vis-à-vis another state of which the injured party is also a national, as the person concerned is regarded by that state as its own national. The Swiss authorities can only protect the rights of Swiss citizens with dual nationality vis-à-vis third-party states if their primary nationality is Swiss. The International Court of Justice pronounced on the establishment of primary nationality in the Nottebohm case.

It is still possible for Switzerland to intervene against the state of origin in cases of grave and repeated violations of central principles of international law as embodied in the European Human Rights Convention or in common law (for example the right to life, the right to corporal integrity and freedom from torture, the right to a fair trial).

Where the nationality of juridical persons is concerned, the are two criteria that lead a state to extend diplomatic protection:

• the registered office
• control or the predominant interest.

Switzerland applies the predominant interest criterion. This is assumed if the effective majority of the equity is in Swiss hands. If there is no majority, the determining factor is which group exercises a decisive influence on the company. Switzerland can thus intervene on behalf of a foreign company based in Switzerland, and also on behalf of a company based abroad – provided that Swiss economic interests are affected to a sufficient extent.

A further precondition for diplomatic protection is that the injury must be the consequence of Conduct on the part of the receiving state in breach of international law. Examples of this are the refusal of rights, imprisonment without trial, discriminatory or arbitrary expropriation, nationalisation, seizure without compensation.

A state cannot extend diplomatic protection and file a complaint or bring a charge unless the person affected has exhausted all means of legal redress within the foreign country, insofar as it would have been possible and reasonable to expect him to do so. This condition gives diplomatic protection a supplemental character. It would be premature, after all, to accuse a state of a breach of international law if it had had no opportunity of righting the wrong.

There are circumstances, however, in which it is not essential for all means of legal redress within the foreign state to have been exhausted, for example if such means do not exist or are ineffective or inadequate.

Diplomatic protection cannot be extended if the statute of limitations applying to the offence complained of has expired. The same applies if the claim by the home state of the injured person has been forfeited.

The foundations of diplomatic protection were stated in 1924 by the Permanent International Court of Justice in connection with the Mavrommatis case: "It is an elementary principle of international law that a State is entitled to protect its subjects, when injured by acts contrary to international law committed by another State, from whom they have been unable to obtain satisfaction through the ordinary channels. By taking up the case of one of its subjects and by resorting to diplomatic action or international judicial proceedings on his behalf, a State is in reality asserting its own rights – its right to ensure, in the person of its subjects, respect for the rules of international law." Diplomatic protection thus has its origins in the idea of a fusion of private and state interests.