International organizations — Officials — Immunity — European Community — Permanent Delegation to international organizations in Geneva — Employees of foreign nationality — Exemption from social security contributions — Whether person enjoying exemption entitled to make voluntary contributions — Vienna Convention on Diplomatic Relations, 1961, Article 33 — Contributions made in good faith under mistake — Whether refundable

Treaties — Effect on third parties — Vienna Convention on Diplomatic Relations, 1961, Article 48 — Whether Convention applicable to representatives of inter-State organizations — Application by analogy and special agreement — Whether social security provisions of Convention applicable to members of Permanent Delegation of European Community to international organizations in Geneva — The law of Switzerland