The well-developed concepts of issue preclusion are beginning to have application in criminal proceedings, and not just within the jurisdiction in which the rendering courts sits but beyond the jurisdiction as well. This article suggests that there are situations in which full faith and credit may require that a criminal proceeding in forum I be given preclusive effect in forum II. However, it must be emphasized that a judgment can have preclusive effect only if the requirements of the rendering State are met. These requirements are (1) a precluded party with the incentive and opportunity to litigate the issue fully, (2) the decision on the issue that was necessary for the final judgment, and (3) a precise identity between issues in the first litigation and the present litigation. Precision of analysis is absolutely essential when a litigant asserts issue preclusion, as in Mulligan v. Schlachter, in which the court of appeals held that a trial does not necessarily provide adequate recompense for constitutional deprivations. The need to analyze the legal problems carefully is also clearly present in the full faith and credit context. For example, a situation in which an individual has been killed by an individual who will inherit from the deceased may lead to full faith and credit issues that require particularly careful analysis. The death of the owner of the property may be in State I, and any conviction would be in that State. However, if the convicted killer attempts to take property in State II, the murder conviction in State I may be included in upholding State II's laws concerning unlawful inheritance. But if State II has no statutes barring the killer from taking property, the passage of property in forum II is controlled by the law of that jurisdiction and not by the law of forum I. It must also be recognized that issue preclusion as part of full faith and credit will tend to be one-sided. The overwhelming number of interjurisdictional issue preclusive cases, under full faith and credit, will be against a prosecuted individual; only on rare occasions will a prosecuting authority be precluded in an interjurisdictional situation. Over 110 footnotes are provided.