Collateral estoppel is a doctrine of finality designed to limit relitigation of issues previously determined. It is founded on the concept of judicial efficiency tempered with fairness. The contexts for use of collateral estoppel are varied. The burden of proof issue, however, affects its use in all contexts. The use of collateral estoppel in a civil action following a criminal prosecution is constitutionally permissible. The courts continually grapple with the problems of whom to preclude, who is allowed to preclude, and what issue was previously determined. The various methods of resolving criminal actions pose special problems, as do certain procedural settings. RICO, in section 1964(d), explicitly provides for the use of collateral estoppel by the United States in a civil action following a RICo criminal prosecution. Although RICO is based on antitrust principles, the collateral estoppel provision is stronger than the corresponding prima facie evidence provision of the antitrust law. The antitrust provision creates a rebuttable presumption, while collateral estoppel, once applied, is an absolute preclusion. A person not a party to the prior RICO action should be able to use a RICO conviction offensively in a subsequent civil action. This conclusion follows from the basic principles of collateral estoppel as developed in the criminal-civil context; however, an argument can be made that a private party should not be allowed to use collateral estopel against a party convicted of a RICO offense. Although no case has yet involved the use of collateral estoppel in a civil action following a RICO conviction, hypothetical examples are presented which involve actual fact patterns as much as possible. A total of 117 footnotes are provided. For additional material on RICO, see NCJ 78839.