Just because a witness or party has written evidence to support his claim does not automatically mean that a judge will allow that evidence to be presented to the jury. One test evidence must meet in order to be deemed admissible by the court is that the evidence must be authentic.
Authentication refers to a rule of evidence which requires that evidence must be sufficient to support a finding that the matter in question is what its proponent claims. The "authenticity" rule relates to whether the subject of an evidentiary offering (generally a tangible thing), is what it purports to be. This is a legal way of saying that evidence must be proven to be genuine to be admissible.
The issue of authenticity must be determined at two stages of a proceeding. First, the court must determine if the proffered item appears sufficiently genuine so that its admission could assist the fact-finder (usually the jury). Second, the fact-finder must ultimately decide whether he believes that the evidence is actually genuine.
For instance, evidence may be authenticated by the testimony of a witness that a matter is what it is claimed to be; as in the case of a witness testifying that a picture accurately represents the object in the photograph.
Authentication of evidence may also be accomplished when it involves a writing authorized by law to be recorded or filed which has been recorded or filed in a public office, or a purported public record, report or statement. Telephone conversations may be authenticated by evidence that a call was made to the number assigned at the time by the telephone company to a particular person or business.
However, the fact that evidence is found by the court to satisfy the authenticity requirement does not mean that it is necessarily admissible. Authenticated evidence may be excluded by other rules such as those that relate to hearsay. For instance, a police report by an investigating officer can be authenticated by having the policeman testify at trial that the report is genuine and was created by him. However, that report is hearsay, since it is a writing, and would not be admissible under the hearsay rule even though it initially became authenticated by the officer's testimony.
Authentication of evidence is an important factor for your attorney to consider when the case proceeds to trial. Some states have laws that provide a procedure to have evidence deemed authentic. For instance, some states provide that a person's medical records are automatically deemed authentic if the healthcare provider who provides the records certifies in writing that the copies of the records are a true and accurate copy.
The rule of authentication must be applied in conjunction with the other rules of evidence to ensure that the judge will allow the evidence to be presented to the jury. There is nothing more devastating to a case than a court's exclusion of valuable written evidence on the grounds that the attorney has failed to properly authenticate the evidence.