The cases are crimes for which there is no convictable perpetrator and crimes in which the degree of responsibility of the actual perpetrator may be less than that of the accessory. The doctrinal matters that arise are, respectively, innocent and semi-innocent agency. The doctrine developed in the context of the narrow theory of accomplice liability: the common law embraces a dogma that without someone who can be shown, as against an accessory, to have been convictable as perpetrator, there can be no conviction as accessory. Criminal legislation should clearly cover conduct before a conviction is brought in -- if the words of the legislation are not satisfied, it is unconstitutional to convict. It might be argued that so long as a criminal code or a complicity statute makes provision for the conviction of persons who cause prohibited acts to be performed by another, the objection on the basis of legality loses its force. The law is now clearer; less complicated; and more principled in England, Canada, New Zealand, and those United States jurisdictions that make no special provision for innocent agency than it would be under the current codification proposals. It may well be that a more thoroughgoing reappraisal of the law of complicity is what is required. 134 footnotes