Evidence admissibility regulations are the standard for whether or not a piece of evidence will be considered in a court case. Evidence laws determine what testimony, physical evidence or exhibits, or documents will be allowed to be shown during the trial. There are several ways that the admissibility of a piece of evidence is determined, but most fall under one of two factors.
The first factor for evidence admissibility is whether or not the evidence is relevant to the case. In order to determine relevancy, the evidence must be shown to be essential to the facts of the case. It must either help to prove or disprove a presented fact or theory. For example, if a fingerprint left at the crime scene matches the suspect's prints, that would be allowed because it proves that the suspect was at the crime scene. Something found at the crime scene, such as a food wrapper, that has no direct relation to the suspect would probably not be allowed, unless it could be tied to the case in some other way.
The second evidence admissibility factor is whether or not the evidence may cause more harm than good. This is a matter of balance. If the evidence may cause unnecessary prejudice or confusion to the jurors, it will probably not be allowed to be shown. If the evidence could be considered misleading, or if it is a waste of time for the evidence to be presented, the judge may rule that it is unnecessary to the trial.
An example of misleading evidence would be circumstantial evidence. If the suspect's fingerprints were at the crime scene, it would appear that the suspect was at the scene, very possibly at the time of the crime. However, if the crime scene was a place that the suspect frequented often, the fingerprints would probably be ruled misleading, because the prints may have been left at any time. For circumstantial evidence to be allowed, there has to be enough of it to prove that the suspect committed the crime.
Evidence admissibility regulations forbid some kinds of evidence, such as hearsay. If a witness takes the stand, and testifies about what someone else said about the case, that is hearsay. For example, if a woman is sitting in a Laundromat, and overhears two men talking about how their friend committed a crime, that woman could not testify in the trial.
Although most evidence is presented before the trial begins, some evidence will be admissible during the trial, if it is essential to the case. It is up to the judge trying the case to consider what evidence can be used. Judges are very familiar with evidence admissibility, and can determine what evidence will help the jurors reach a decision and what evidence will confuse or sidetrack them, making it more difficult for them to reach a fair and unbiased verdict.
