The Federal Rules of Evidence (FRE) is a code of evidence law governing the admission of facts by which parties in the United States federal court system may prove their cases, both civil and criminal. The Rules were enacted in 1975, with subsequent amendments. The Rules were the product of protracted academic, legislative, and judicial examination before being formally promulgated in 1975. U.S. states are free to adopt or maintain evidence rules different from the Federal Rules, but a substantial majority have adopted codes in whole or part based on the FRE. Because they govern the initial presentation of evidence in a trial, the Rules primarily serve to govern federal trial courts rather than appellate courts, as appellate courts, due to their function and scope address very few questions touching upon the facts of a case. Appellate courts do, however, monitor the application of the rules to ensure consistent application and coherent development of the federal common law of evidence. The Rules are also a focus of most Evidence courses in American law schools. In general, the purpose of rules of evidence is to regulate the evidence that the jury may use to reach a verdict. Historically, the rules of evidence reflected a marked distrust of jurors. The Federal Rules of Evidence strive to eliminate this distrust, and encourage admitting evidence in close cases. Even so, there are some rules that perpetuate the historical mistrust of jurors, expressly limiting the kind of evidence they may receive or the purpose for which they may consider it. At the same time, the Rules center on a few basic ideas - relevance, unfair surprise, efficiency, reliability, and overall fairness of the adversary process. The Rules grant trial judges broad discretion to admit evidence in the face of competing arguments from the parties. This ensures that the jury has a broad spectrum of evidence before it, but not so much evidence that is repetitive, inflammatory, or unnecessarily confusing. The Rules define relevance broadly and relax the common-law prohibitions on witnesses' competence to testify. Hearsay standards are similarly relaxed, as are the standards for authenticating written documents. At the same time, the judge retains power to exclude evidence that has too great a danger for unfair prejudice to a party due to its inflammatory, repetitive, or confusing nature or its propensity to waste the court's time.