What is Evidence Law?

Mary McMahon
Mary McMahon

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.

Evidence law dictates what items are admissible during a trial.
Evidence law dictates what items are admissible during a trial.

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.

"Real evidence" refers to the potential murder weapon.
"Real evidence" refers to the potential murder weapon.

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.

Evidence from crime scenes must be collected using specific procedures to prevent contamination.
Evidence from crime scenes must be collected using specific procedures to prevent contamination.

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.

Video recordings are known as documentary evidence.
Video recordings are known as documentary evidence.

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.

Following evidence law is extremely vital in serious criminal cases.
Following evidence law is extremely vital in serious criminal cases.
Evidence law also pertains to testimony an officer may collect while on patrol.
Evidence law also pertains to testimony an officer may collect while on patrol.
Under evidence law, in order for evidence to be admissible, it must be relevant, material and competent.
Under evidence law, in order for evidence to be admissible, it must be relevant, material and competent.
Chain of custody ensures that evidence was in continuous possession of one or more persons until it was entered at trial.
Chain of custody ensures that evidence was in continuous possession of one or more persons until it was entered at trial.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

EarlyForest

@pleats -- You might want to read over some evidence acts or even, if you're really interested, a book called "Law of Evidence for Criminal Justice Professionals". That will give you a deeper understanding; if you're just looking for basics, try an Emanuel Law Outline -- they usually are pretty succinct.

pleats

Do the rules for trial evidence in defense law differ from the rules for evidence in trial at common law? I'm finding the whole evidence thing really confusing, can somebody simplify it for me?

rallenwriter

When my boyfriend was studying evidence in law school, I would help quiz him on his evidence law exams, and that stuff is incredibly complicated. He focused on the Federal rules of evidence, so I can only imagine how crazy it gets when you get down into appeal courts and local courts.

All those evidence law books were way too much for me -- I'll stick with doing my own thing, and he can take the world to trial!

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