The most difficult problems in criminal theory are generated by dissonance between reality and belief, between the objective facts and the actor's subjective impression of the facts. (1)
Suppose Alice hits Bert on the head. Prima facie, Alice has done something that she ought not to have done: in hitting Bert she has harmed him, or violated a right of his not to be hit on the head, or interfered with his ability to determine his own ends. (2) And yet it may be that Alice should not be punished for hitting Bert, either because her action is justified, or because she is excused.
It has become commonplace to distinguish excuses from justifications and to point to an asymmetry between the two. According to one prominent view, (3) an excuse is something that calls attention to features of the agent at the time at which she performs an action. Somebody claiming to be excused does not deny that the action in question was wrongful, but denies that she was appropriately responsible for its performance. A justification, on the other hand, calls attention to features of the situation or circumstances at the time at which an agent performs an action. Somebody claiming a justification does not deny responsibility for the action in question, but denies that the action was wrongful in the circumstances. (4) More to the point, a justification entails that the accused has done nothing wrong, whereas an excuse entails that the accused has done something wrong, but that for various reasons her punishment should be reduced; or as Peter Westen puts it, "[t]he difference between justification and excuse, properly understood, is as basic and simple as the distinction between, "I did nothing wrong," and, "Even if I did, it was not my fault." (5) This view of the distinction between justification and excuse is, broadly speaking, normative in nature, focusing on concepts of fault and responsibility.
According to another view, the difference between justification and excuse is related instead to the different role played by each in the criminal law. So, for example, Meir Dan-Cohen (6) distinguishes conduct rules (legal rules addressed to the public) from decision rules (legal rules addressed to officials) and suggests that justifications are conduct rules and are part of the theory of crime, whereas excuses are decision rules and are part of the theory of punishment. On this view, justifications have to do with whether a crime has been committed at all, whereas excuses are concerned with whether and to what extent the state may punish wrongdoers after the fact. In contrast to the normative analysis sketched above, this analysis of the distinction between justification and excuse is, broadly speaking, functional in nature.
I take no stand on which analysis is to be preferred, although my suspicion is that they are, at bottom, not so very different: justifications are conduct rules, and belong to the theory of crime, precisely because somebody who acts with justification does nothing wrong. Excuses are decision rules, and belong to the theory of punishment, precisely because somebody who asks to be excused has done something wrong but seeks exculpation on the grounds that she was not at fault for doing so.
Nonetheless, although the distinction between justification and excuse is reasonable enough as a point of departure it leaves important questions unanswered, largely because it is not clear what facts are relevant to determining when an individual should be regarded as having acted with justification and when an individual should merely be excused for something that she did. It is not clear, in other words, whether an account of justification ought to be subjective or objective in nature. In "Competing Theories of Justification: Deeds v. Reasons" and elsewhere, Paul Robinson argues that justification ought to be understood in an objective manner. (7) In Robinson's view, the objective account of justification "generates liability results that are more just and that better match our collective intuitions of what is just," "lays bare the distinctions that are relevant to determining liability," and "allows a clearer analysis and a better perspective from which meaningfully to debate the competing issues. …