Основания допустимости доказательств в американском процессуальном праве.

In common law, a foundation is sufficient preliminary evidence of the authenticity and relevance for the admission of material evidence in the form of exhibits or testimony of witnesses. Although the word "Foundation" does not appear in the Federal Rules of Evidence, scholars have argued that its existence is displayed, albeit implicitly, when viewing all the rules in context. Material evidence is important evidence that may serve to determine the outcome of a case. Exhibits include real evidence, illustrative evidence, demonstrative evidence, and documentary evidence. The type of preliminary evidence necessary to lay the proper foundation depends on the form and type of material evidence offered. Further, a proper foundation must be laid with respect to witness testimony. The type of questioning and evidence necessary to properly lay a witness foundation differs based on what the witness is testifying to, and in what capacity they are testifying. The lack of foundation is a valid objection that an adverse party may raise during trial.

The Federal Rules of Evidence states rules regarding a piece of evidence's relevancy and whether or not it is admissible. F. R. E. 402 states relevant evidence is admissible unless otherwise excluded by: "The U. S. Constitution, a federal statute, the Federal Rules of Evidence, or other rules proscribed by the Supreme Court." F. R. E. 402 further provides that irrelevant evidence is inadmissible. The rule states: "Evidence is relevant if: (a) it has any tendency to make a fact more or less probable than it would be without the evidence; and (b) the fact is of consequence in determining the action." This process of testing evidence's probative value requires a process of legal analysis and reasoning. Evidence that is irrelevant is inadmissible in court according to F. R. E. 402. F. R. E. 403 lists some of the reasons that relevant evidence would be excluded. These reasons include: the likelihood of the jury becoming unduly prejudiced to a party, and a likelihood that the evidence will cause the jury to confuse the issues or be mislead, etc. In Old Chief, the defendant was on trial for an altercation that resulted in him firing a weapon. This may be done outside of the presence of the jury at a preliminary hearing.

The Federal Rules of Evidence mandate that evidence be authentic in order to be introduced at trial. This means the proponent of evidence must "produce evidence sufficient to support a finding that the item is what the proponent claims it is." This may include facts with regards to: distances in the photograph, inaccuracies or distortions, the camera the photograph was taken with, the circumstances under which the photo was taken, etc. First, the proponent of the evidence must request that the item be marked for identification. The process differs when the witness is a lay witness or an expert witness.

A lay witness is a non expert who may only provide opinions based upon their own personal knowledge of particular facts at issue in a case. F. R. E. 602 provides the rule relating to the necessary foundation that must be laid for a witness to testify on a particular matter. For example, to establish a basis of a lay witness's personal opinion of a defendant, an attorney may ask the witness questions such as: whether they know the defendant? How do you know the defendant? How long have you known the defendant? That standard, while superseded by 702, is still a valid challenge to expert testimony. The Daubert standard inquires: 1) whether the expert's scientific method has been subject to testing, 2) whether the method has undergone peer review and been published, 3) how fallible is the method, 4) whether the method is subject to particular standards when it is undertaken, 5) whether the method is accepted in the scientific community in which it is employed?