This lecture offers some thoughts on the perils of unreflective moral enthusiasm, what I call moral excess. It proceeds by identifying three current instances of it, particularly in the criminal law, and offers reflections on features of morality that are obscured by it. The first instance concerns the moral obligations of lawyers, not only in criminal matters, but in all areas. Some today find moral fault with lawyers who represent morally disagreeable clients or causes on the premise that whatever is wrong for a private person to do is wrong for a lawyer to do. I argue that this is an overstatement which undervalues the moral force of the institutional professional role. The second instance consists of attempts to justify the occasional criminal law doctrine that deprives morally suspect defendants of legal defenses they would otherwise enjoy. I view this as itself morally suspect insofar as it invites subjective judicial moralizing antithetical to rule-of-law values. The third instance is the common criticism of the criminal law that it is morally defective to the extent that it fails to accord a legal excuse to defendants who are morally excusable because they are below standard in temperament, intellect or character. This position, I argue, is first, insensitive to the imperatives of an institutionalized system of punishment, and second, offers a concept of moral excuse so broad as to threaten the practice of moral blaming itself. I conclude with observations on the paradox that sometimes it can be "right" to do the wrong thing, and sometimes "wrong" to do the right thing.