State immunity — Jurisdictional immunity — Foreign States — Holy See — Dispute concerning sale of land — Scope of entitlement of Holy See to jurisdictional immunity — Distinction between acts performed jure gestionis and jure imperii — Land obtained to provide premises for diplomatic mission — Whether disposal of such land constituting act performed jure imperii

States — Holy See — Vatican City — Status under international law — Lateran Treaty, 1929 — Entitlement of Holy See to jurisdictional immunity

States — Sovereignty and independence — Executive certificate — Determination by executive of entitlement to State immunity and diplomatic immunity — Whether binding upon municipal courts

Relationship of international law and municipal law — Constitutional provisions — Philippine Constitution 1987, Article II(2) — Incorporation of generally accepted principles of international law into municipal law — The law of the Philippines