Federal Rules of Evidence control judges and lawyers. State rules are typically modeled on these Federal rules.
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 purpose of rules of evidence is to regulate the evidence that the jury may use to reach a verdict.
... 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.
These rules govern the introduction of evidence in proceedings, both civil and criminal, in Federal courts. While they do not apply to suits in state courts, the rules of many states have been closely modeled on these provisions.
Evidence overview.
