Reflections on ‘Reasonableness’ in the Restatement (Fourth) of US Foreign Relations Law

Abstract

Where the Third Restatement contained an ambitious ‘rule-of-reason’ that it asserted was customary international law, the Fourth Restatement is much more cautious, placing an emphasis on jurisdictional self-restraint as a matter of voluntary comity. This hesitance is understandable given the established lack of state practice supporting second-order interest-balancing requirements or rules of priority. It is thus repeatedly asserted that United States’ practice based on its domestic principles of prescriptive comity is not done out of a sense of obligation, and is therefore not evidence of what international law requires. This article has argued however, that more attention is needed for the opposite dynamic, namely the role of international law in (in)forming comity. As state jurisdiction is the lawful exercise of sovereign power, the principle of sovereign equality, and the related principles of non-interference and non-intervention, continue to condition how this is done. While they may not manifest themselves as a customary ‘rule-of-reason’ or other rule of priority, they do reinforce comity doctrines. As such, while acts of comity may go beyond what is required by international law, they cannot be characterised as entirely voluntary. Evidentiary dilemmas certainly remain when seeking to determine the precise contours of the binding norms themselves. The principle of consistent interpretation with international law is a particular catalyst in blurring the motives behind state practice. Arguably, rather than focusing on whether a norm should apply, these principles may be more helpfully operationalised as an instruction towards legislatures, cautioning them to design their measures ‘considerately’, in a manner that takes into account the legitimate interests of other states. In light of our increasing interdependence, ‘reasonableness’ remains of relevance for the law of state jurisdiction, and an issue on which we are yet to hear the last word.