Suppression of evidence is a term used in the United States legal system to describe the lawful or unlawful act of preventing evidence from being shown in a trial. This could happen for several reasons. For example, if a judge believes that the evidence in question was obtained illegally, he can rule that it not be shown in court. It could also refer to a prosecutor improperly or intentionally hiding evidence that he or she is legally obligated to show the defense. In the latter case, this would be a violation of the 5th amendment to the United States Constitution. This can result in a mistrial in the latter case and/or the dismissal of the prosecutor.