How is Evidence Admissibility Determined?

Margo Upson
Margo Upson

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.

Fingerprints from a crime scene might be admissible evidence.
Fingerprints from a crime scene might be admissible evidence.

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.

Laws determine whether evidence can be presented during a trial.
Laws determine whether evidence can be presented during a trial.

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.

Evidence admissibility regulations do not allow hearsay, but would allow other forms of testimony.
Evidence admissibility regulations do not allow hearsay, but would allow other forms of testimony.
Margo Upson
Margo Upson

Margo has a varied academic background, which has involved everything from psychology and culinary arts to criminal justice and education. These wide-ranging interests make her an ideal wiseGEEK writer, as she always enjoys becoming an expert on new and unfamiliar topics.

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Discussion Comments


@ddljohn-- But in that case, the candy wrapper would be an admissible evidence because it gives insight about the crime.

I think that judges do consider all of the evidence that is presented before determining which is admissible and which is not. The most important issue about admissible evidence is relevancy as the article also mentioned. If a piece of evidence enlightens an aspect about a case, if it takes the case forward and brings out new facts, it's relevant to the case and will be admissible.

In that example, the candy wrapper would not be admissible if it said nothing about the crime, the victim or the criminal. So a lot of it is based on details. I agree with the article that judges are used to various types of evidence and know which are relevant and important very easily.


But how do courts know whether an evidence is admissible without actually considering it? Who knows, that random piece of candy wrapper may have someone's DNA showing that yet another person was at the place of the crime.


Evidence may also not be admissible in cases where law enforcement officials did not follow procedures. For example, if evidence was collected during an unlawful search, then that evidence cannot be submitted in court. The same applies to evidence collected in a way not suitable to evidence collection guidelines.

So it's vital for officials to follow all procedures very carefully, otherwise the evidence collected will be of no use.

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