Legislatures and judges have devised a variety of evidentiary devices to structure the jury's decisionmaking and to guide its inferential process toward a rational result. In the years since the Supreme Court's ruling in 'In re Winship' (1970), in which the reasonable doubt standard was constitutionalized, these devices have been challenged as undermining the requirement of proof beyond a reasonable doubt. It is suggested that the superficially distinct evidentiary devices employed in criminal trials, including affirmative defenses, placement of burdens of production and the concomitant possibility of a directed verdict on an issue, judicial comment on the evidence, and instructions on presumptions and inferences, are actually very similar. Their primary unifying trait is that they all modify the evidentiary relationship of the parties at trial by manipulating burdens of persuasion. The Supreme Court has failed to provide satisfactory guidance in this area. However, because more refined tools are now available to the Court and because the various evidentiary devices are clearly seen as differing ways of allocating burdens of persuasion, and adequate method of analysis is available. The Court must address the real issues, i.e., which facts must constitutionally be established at trials and to what extent will trial courts be permitted to give rational guidance to juries on such factual issues. Trial courts will require some latitude in order to give rational guidance to juries. The Court's 1977 decision in 'Ulster County Court v. Allen' may have moved in the proper direction in its analysis of instruction as though it were a comment on the evidence. Article footnotes total 194. (Author abstract modified).