Excusing Mistakes of Law

The theory of excuses is notoriously fraught with difficulties. In fact, it is not clear that there can be a true theory of excuses. It seems possible that there are many sufficient conditions for excuse but only messy disjunctive necessary conditions. Still, say that we could identify a principle of the form “If defendant D has a false belief that p and _____, then D is excused”, and that the principle had the following feature: it is true whenever p is a non-legal proposition, but it is false quite often when p is a proposition about the law. Then it would follow that there is an asymmetry in the excusing force of mistakes of fact and law. If there is a principle like this, then although there may be other principles of excuse that apply promiscuously to mistakes of fact and law, there is at least one way in which mistakes of fact can excuse that doesn’t stretch naturally to mistakes of law. Providing such a principle is this paper’s aim. However, the issue that is raised by mistakes of law is of broad importance to moral philosophy. At its heart, the question concerns the conditions under which a person with false normative beliefs — beliefs concerning, for instance, what one is permitted to do — is excused on those grounds, and what the relationship is between such conditions and those under which false beliefs about non-normative matters excuse. And like any question concerning excuses, the underlying and driving issue concerns the nature of responsibility itself. To identify a valid principle of excuse that serves to explain the asymmetry between the excusing force of mistakes of fact and law is to identify something fundamental about the nature of responsibility, something that is illuminated by its asymmetrical relation to normative and non-normative error.