Professor McLachlan’s latest book stands at the intersection of what are often regarded as doctrinally disparate branches of law when examining the legal principles governing the regulation of foreign relations. Focusing on the external exercise of public authority by Australia, Canada, New Zealand, and the United Kingdom, this study considers three important broad issues relating to the law of foreign affairs.

The first of these, explored in Part II, is how foreign relations power is distributed between each of the three organs of government. Public lawyers will no doubt be drawn to the discussion analyzing the rebalancing of power in the modern constitution. Once the exclusive concern of the executive, recent developments have seen a new and strengthened role for the legislature and judiciary in holding the executive to account when making decisions on matters of foreign relations. An additional area considered in this part of the study is the limitations imposed on a state when enacting legislation over conduct and events performed outside its borders. Although this is, in itself, a broad topic of public international law, McLachlan considers it more narrowly within the book’s central argument, suggesting that the law of foreign relations performs an allocative function between the different actors in the legal system(s).

With an increasing number of public acts now being performed by states abroad, the second broad theme of this book, explored in Part III, is the possibility for aggrieved individuals to seek legal redress for abuses stemming from these activities. Remedies may be provided either by direct actions being brought against the state before its own courts, or by states invoking responsibility on the international plane through diplomatic protection. McLachlan revaluates the limitations preventing these claims being successfully brought that are presented by the act of state doctrine, the territorial nature of human rights obligations, and there being no duty on states to exercise diplomatic protection. Finally, Part IV of the study examines how foreign states are treated in domestic legal systems, with attention being given to issues surrounding the recognition of foreign states and to the position of foreign states as both a claimant and defendant in legal proceedings.

The range of individual topics considered in detail will appeal to a very wide audience. However, the book’s particular strength is in coherently bringing together the different concerns of constitutional law, public international law, and—to a lesser extent—the conflicts of law, in presenting a modern treatise on the law governing foreign relations. This is where McLachlan makes an important and excellent contribution to the academic literature, which has for many years lacked a study of this kind.