Collateral estoppel is a judicial doctrine that precludes a party from relitigating an issue that has been fully and fairly litigated in a prior adjudication. The basic requirements of the doctrine are identity of issue, litigation in fact, a valid and final judgment on the issue, and a determination that the issue was essential to the prior judgment. The doctrine functions to conserve judicial resources and, in criminal trials, protects rights embodied in the double jeopardy clause. Its underlying rationale is that finality of judgment should be respected even if an issue litigated is integral to a subsequent proceeding. The significance of recognizing collateral estoppel as a constitutional requirement in revocation proceedings following an acquittal is two-fold. First, it will function to protect those interests that underlie the double jeopardy clause. Few would contend that imprisonment resulting from a parole or probation revocation is any less punitive than that which may follow directly from a conviction. It is the threat of such punishment and the anxiety which results that form the framework of the double jeopardy clause. Where interests preserved under the clause are identical to those implicated by a pending revocation proceeding, there is little logical support for the argument that comparable protections cannot be found in the ample reaches of the 14th amendment. The second result of recognizing collateral estoppel as a constitutional requirement in revocation proceedings following an acquittal would be to preserve traditional constitutional respect for acquittal. To permit the State to circumvent a prior determination by invoking that nebulous and ill-understood margin of proof between the 'preponderance' standard and the 'reasonable doubt' standard offend the traditional jurisprudential emphasis on finality of judgment. A total of 172 footnotes are provided.