Diplomatic relations — Immunity — Family of diplomatic agent — Entitlement of wife of diplomatic agent to immunity from taxation in receiving State — Vienna Convention on Diplomatic Relations, 1961, Articles 34 and 37

Treaties — Application by municipal courts — Interpretation — Intention of the parties — Assumption that parties to a treaty intend to apply rules of customary international law — Belgium-Netherlands Convention for the Avoidance of Double Taxation, 1970 — The law of the Netherlands