State Immunity, Diplomatic Immunity and Act of State: A Triple Protection Against Legal Action?

The relationship between State immunity and diplomatic immunity has always been a rather complex one. The two concepts undoubtedly have a common juridical background in the form of the concepts of sovereignty, independence and dignity.1 On the other hand, recent developments in both fields have seen a move towards a more functional-based approach. Thus, in relation to diplomatic immunity, the dominant theoretical basis is that of functional necessity.2 As regards State immunity, recent developments in both international law3 and, more particularly, in UK law4, from absolute to restrictive State immunity, have resulted in a more functionally orientated approach, that is, a shift of emphasis in matters of State immunity from immunity ratione personae to immunity ratione materiae.5 Now two recent cases in the United Kingdom have raised the possibility that, in the case of diplomats at least, the two concepts may be combined to provide a double immunity for diplomatic agents against civil suit. More controversially, the cases have raised the possibility of a third type of protection based upon immunity ratione personae in what could be said to amount to a modified act of State doctrine. The cases in question are Propend Finance Pty Ltd. v. Alan Sing and The Commissioner of the Australian Federal Police6 and Re P (Diplomatic Immunity: Jurisdiction).