As any good constitutional lawyer will know, and be more than happy to expound on at length, the interaction between international law and national law is complex and difficult. It is easy enough at an academic level, or before the courts, to invoke international norms in national, domestic legal matters with little more than a general or passing regard for their constitutional status. The focus falls naturally upon their content, adding weight and advantage to press home a desired legal result, and upon the impression of global, trans-jurisdictional comity on at least that legal rule. But status and legal stature prove a somewhat more pressing immediate issue when the time comes actually and concretely to apply them. Countering the pressures of an internationalised world are the equal pressures of maintaining domestic legitimacy and constitutional loyalty. Although the event horizon for the courts may stretch to international distances, the practicable and effective scope of sight would seem to remain limited to national boundaries, if only because the courts are products of and representatives of such a nationaloriented constitutional footing. That constitutional tension serves as the impetus for this book. The central question is to what extent judges respect and enforce the national doctrine of the separation of powers in recognising and enforcing norms of international law. In a more compact form perhaps, the issue is what limits the separation of powers sets on the possibilities of national courts in various countries to interpret and apply norms of public international law. This is framed against the background of the ‘‘globalisation’’ of law. The question is thus to be read within a broader perspective of whether the state should be viewed as a solid, closed entity, or whether globalisation breaks through the boundaries set by the separation of powers with the result of a broader scope of powers for national courts in the field of the interpretation of international norms.