Evidence law is the body of law which pertains to evidence. For successful pursuit of a case in court, whether it is a murder trial or a small claims dispute, it is necessary to present evidence to support or undermine the case, depending on which side one is arguing. As a result, a number of laws have been developed to dictate what can be considered evidence, the types of circumstances in which evidence may be admitted, and what can make evidence inadmissible.
The rules of evidence, as they are known, are followed by the court to determine whether or not something can be entered into evidence. Rules of evidence tend to vary, depending on the level of the court and the nature of the case. When representatives of either side of a court case wish to introduce something into court as evidence, they must demonstrate that it falls under the rules of evidence, and the other side may opt to contest the evidence.
There are four primary types of evidence: testimonial, documentary, real, and demonstrative. Testimonial evidence is the form of evidence with which many people are most familiar, involving testimony in court from someone who has information pertaining to the case. Documentary evidence takes the form of photographs, video, written documentation, or audio, which is introduced to allow people to examine the contents of the document. Real evidence is any item related to the crime, such as a murder weapon, while demonstrative evidence is evidence which is supposed to support or clarify factual information by demonstrating it. A map of a crime scene, for instance, is demonstrative evidence.
Under evidence law, in order for evidence to be admissible, it must be relevant, material, and competent. These rules are designed to rule out evidence which is not related to the crime, evidence which does not add to the case, or evidence which may be unreliable. The rules surrounding testimonial evidence can be especially complex, addressing concerns such as hearsay and circumstantial evidence which sometimes tread on a fine line, according to evidence law.
Evidence law is also designed to ensure that evidence which has been compromised is inadmissible. Evidence tampering and other forms of manipulation, including a lack of a clear chain of custody for the evidence, can result in having evidence thrown out of court. For this reason, law enforcement officers need to be familiar with evidence law, to ensure that they collect, store, handle, and process evidence properly.