A distinguishing feature of state immunity, the principle of customary international law which posits that a sovereign state cannot be sued before the courts of another state without its consent, is the predominant role played by the domestic judge in its development. Evolving primarily through the judgments of national courts, the international law of state immunity has emerged from the confluence of domestic judicial practices. This feature, as Xiaodong Yang argues in his treatise State Immunity in International Law, requires a reconceptualisation of the sources of international law and its relationship to domestic legal systems. Moreover, it underscores the importance of a comparative legal approach to the law of immunity, such that “a survey of foreign domestic court cases is now more than a comparative exercise for information purposes only: it forms the very essence of the process of identifying the binding legal rules” (27).
Yang opens his exposition of the law of state immunity by challenging its theoretical foundations. He exposes the inadequacy of the conventional legal bases upon which it relies – namely, the sovereignty, equality, independence and dignity of states and the maxim par in parem non habet imperium – by demonstrating them to be circular and self-defeating. Individually and collectively, these rationales are simply attributes of statehood, reduced to the tautology that “a State enjoys immunity because it is a State” (45). Since statehood cannot in itself create an inherent right to demand that another State cede jurisdiction, immunity must therefore have been a “matter of grace” (50). While the International Court of Justice's pronouncements on the opinio juris underpinning state immunity in the Jurisdictional Immunities (Germany v Italy) case (ICJ Reports 2012, 99, at 123), a judgment delivered after the publication of the book, may challenge this analysis, Yang observes that in any event, national courts are no longer preoccupied in practice with such metaphysical debates and have simply incorporated immunity into their arsenal of procedural rules.
Throughout the book, Yang casts two prevailing, if opposing, trends into relief. First, he observes the unification of the law of state immunity, culminating in the “triumph of the doctrine of restrictive immunity over that of absolute immunity” (6). Restrictive immunity is a corollary of the metamorphosis of the modern state into an economic actor which has entered the market-place...
