A long-term and significant effect of the English Reformation of the 1530s has been the marginalisation of scholarship on religious law. Although this has begun to change in recent years, very little attention has been afforded to the defining features of religious law and whether it is useful to talk of a category of religious law. This article seeks to begin to redress this by constructing an understanding of religious law as necessarily having both a religious and legal character. It draws upon the work of Robert Alexy and Niklas Luhmann in particular to propose a necessarily interdisciplinary understanding to further stimulate scholarship on religious law.