Admissible evidence is any testimonial, documentary or tangible evidence that may be presented to a judge or jury to establish if it will be considered in a court case. The evidence must have some indicia of reliability and must be relevant without being prejudicial in order for it to be admissible.
The first factor in determining the admissibility of the evidence is relevancy. Evidence must show essential to the facts of the case. The evidence must show it could help with the investigation of the case or prove or disprove certain facts about the case.
Second factor is balance. The evidence must be studied to show whether it will do more harm than good. If the evidence might show if it will cause confusion or unnecessary prejudice to the court or if may be considered as misleading or a waste of time then it might be inadmissible.
Some evidence is forbidden in the evidence admissibility regulations. Hearsay is one kind of forbidden evidence. One person cannot testify in front of the court if he is not the source of the testimony. If he happens to just overhear two men talking about a certain topic that might be connected with the case, then that man cannot testify in front of the court. Some evidence may also be presented even during the trial. This will depend again on the relevance of the said evidence to the case. The judge has the right to admit evidence which he thinks will help the jurors more.