International law in general — Sources — General principles of law — Generally recognized principle — Application by Arbitral Commission on Property, Rights and Interests in Germany.

Arbitration — In general — Law applied by arbitral tribunals — Generally recognized principle — Application in matters of intervention.

International Court of Justice — Contentious jurisdiction — Procedure — Provisions on intervention — Whether applicable by analogy in arbitral bodies with respect to individuals.

Arbitration — Procedure — Intervention — Arbitral Commission on Property, Rights and Interests in Germany — Rules of procedure of Commission — Lack of rules on conditions of intervention — Application of generally recognized principle — Legitimate interest as basis of intervention — Case-law of Commission — Provisions on intervention in Statutes of international tribunals established at The Hague — Whether relevant in proceedings before Commission.