In his discussion of the nature of law St Thomas Aquinas cites St Augustine's principle that an unjust law ceases by that very fact to be a truly binding one, and this remark provides us with a useful springboard for a discussion of how different institutions have dealt with the occurrence of such a problem within their own systems. There are two principal factispecies envisaged when we deal with such a scenario within the Christian community; when a law has been interpreted erroneously by its officers and when the law is applied by the administration with a rigidity that exceeds the intention of the legislator. In these circumstances, it is arguable that we are dealing not with true law as such but with the corruption of law, non lex seil corruptio legis. The expression corruptio legis is here understood not in a subjective but in an objective sense, i.e. it is not to be understood to refer to the administration or the officials that apply the law but to the legal norm itself. The issues raised by the principle, non lex sed corruptio legis, are not simply ethical but also legal, and the important resolution in Augustine and Aquinas offers a useful window into one of the central problems of comparative administrative law.