Canons of statutory interpretation are sometimes said to promote continuity and stability in the law. Yet it is widely acknowledged that canons themselves often change. The presumption against extraterritoriality is a prime example. It evolved from a rule based on international law, to a canon of comity, to a tool for finding legislative intent. The presumption then fell into disuse for nearly forty years until it was reborn in EEOC v. Arabian American Oil Co. (Aramco) and substantially revised in Morrison v. National Australia Bank Ltd.
This Article makes three contributions. First, it describes the evolution of the presumption against extraterritoriality over two centuries, providing a detailed account of change in an important canon of interpretation. Second, the Article describes the new, post-2010 presumption, arguing — contrary to the conventional wisdom — that the current version of the presumption is superior to previous ones. Third, the Article addresses the problem of changing canons. It argues changing canons constitute a form of dynamic statutory interpretation, which imposes certain responsibilities: to justify the changed canon in normative terms, to explain the need for change, and to mitigate the transition costs.