This article is based on the Louis Caplan Lecture delivered by Prof. Allen on April 10, 1981, at the University of Pittsburgh School of Law. The full text of the lecture, and accompanying footnotes, will be published in the Pittsburgh Law Review. In moments of exasperation , one may be tempted to misapply Mark Twain \u27s comment about the weather and complain that everyone talks about criminal justice, _but no one does anything about it. Sober second thought qmckly reveals, however, that the statement is not literally or even substantially true . Since the eighteenth-century Enlightenment much has been done, for good or ill, about the criminal law and penal justice . Capital punishment was notably curtailed in the western world, and a regi...