Abstract
Occasionally traced back to Byzantine times, the rule that penal statutes are to be interpreted strictly in favor of the subject, also known as the rule of lenity, now finds expression in common law countries across the world. This Article compares the origins and evolution of the rule in Australia and the United States. The comparison is timely because of the current uncertainty in both jurisdictions about the rule's rationale and scope and because of an emerging global trend towards the “constitutionalization” of common law rules of interpretation. In the course of the analysis, various facets of the rule are discussed, including its common law origins; jurisprudential development; purported constitutional foundations; and modifications by state and federal statutes. Tracing the rule's development in each country reveals significant commonalities, but also important differences, in the respective approaches to the interpretation of criminal statutes. Most importantly, despite similarities in the two countries’ constitutional structures, the rule has assumed constitutional significance in the United States but not in Australia. Identification of this marked difference provides an opportunity to reflect on the separation of powers, and the federal structure, of each country.