By reason of the person concerned.
Also ratio personae.
Jurisdiction of a judge in a case which has international elements may depend on the whereabouts of the plaintiff or, as in most cases, the defendant. In certain cases, jurisdiction will depend on the whereabouts of the object of the litigation (i.e. real estate); in others, jurisdiction will depend on whether or not the defendant is within the territory of the court or is a citizen of that court's nation. In the two latter cases, jurisdiction is said to be by reason of the person, ratione personae.
For example, if a Nicaraguan tourist visited a Canadian courthouse and filed a statement of claim against another Nicaraguan in relation to a tort that allegedly occurred in Nicaragua, the Candian court could decline to hear the case because of a lack of rationae personae.
In international law, the maxim has been applied to express the rule of law that only a state privy to an international treaty may be the subjected to the dispute resolution process - judicial or arbitration or other - provided for in the relevant treaty.
If a complaint was levied against an American living in the United States, pursuant to the European Convention on Human Rights, the European Human Rights Commission would not proceed to hear the complaint and would declare that it did not have jurisdiction ratione personae to hear the complaint. Similarly, if a complaint is filed pursuant to an international treaty but against a non-member, the same lack of jurisdiction ratione personae would apply.
Thus, in International Law, authors Wallace and Holliday write of the International Court of Justice:
"Ratione personae: only states may be party to a contentious case before the ICJ...."
States and international agencies utilize several devices to get around the ratione personae difficulty. One such device is to organize the treaty through the auspices of the United Nations, thus enhancing the credibility of the treaty to states and encouraging them to sign on at which point, they are bound ratione personae. Another technique is for domestic criminal or civil law to declare that it would have jurisdiction over, for example, the child sexual abuse offences committed by one of their nationals anywhere in the world. Similarly for terrorist activities or airline traffic offences.
REFERENCES:
- Duhaime, Lloyd, Latin Law Library
- Wallace, R. and Holliday, A., International Law, 1st Edition (London: Sweet & Maxwell, 2006), page 115