On Culpability and Crime: The Treatment of Mens Rea in the Model Penal Code

When conduct has the external attributes of a crime, should further mental elements be required for convic tion, and, if so, what should they be? Decisions have too frequently been imprecise in analysis and inconsistent in re sults, yielding a multitude of single instances which in the ag gregate dilute the moral force that should attach to condemna tion of behavior considered criminal. Criminal liability may justly be based only upon conduct which includes a voluntary act or the omission to perform an act which the actor was physically able to perform. Act or omission are essential pre requisites to liability, but they are not sufficient to establish culpability. The Model Penal Code proposes four concepts to describe the kinds of culpability which are sufficient to es tablish liability: purpose, knowledge, recklessness, or negli gence. The doctrine of strict liability, ignorance and mistake of fact, intoxication, and ignorance and mistake of law are pertinent to establishing liability. One of the most conten tious problems of the penal law concerns the criteria that should determine when individuals whose conduct would otherwise be criminal ought to be exculpated on the ground that they were suffering from mental disease or defect when they acted. The Model Penal Code would exculpate the person who, as a re sult of mental disease or defect, lacked substantial capacity either to appreciate the criminality of his conduct or to con form his behavior to the requirements of law.—Ed.