Admissible evidence is evidence which can be brought forward in a court of law to support or undermine a legal case. In order to be considered admissible, evidence must meet certain standards, with the standards being especially high in criminal cases. Disputes over the admissibility of evidence often play a role in major trials, with lawyers from both sides attempting to suppress evidence which does not favor their case, with the goal of weakening the position of the other side.
Evidence can take a number of forms. In all cases, evidence is considered admissible when it has a bearing on the case, and it can be used to support or disprove facts which are related to the case. For example, in a murder trial, the identity of the murder weapon is relevant and important to the case, but the suspect's history of running out on lease agreements may not be deemed admissible because it is not relevant to the murder.
In the case of evidence presented by a witness, admissible evidence includes evidence from an expert witness discussing the situation and providing information which is accepted and established in the field. For example, a forensic anthropologist could testify about examining a set of human remains, discussing the facts he or she uncovered in the process and presenting his or her credentials to support the facts provided. By contrast, someone who claims to have collected facts using methods which are deemed suspect in the field of forensic anthropology would not be able to testify. Evidence can also be collected from witnesses who saw the crime or were involved in the investigation, such as testimony from a police officer who responded to the scene of a crime, a forensic technician who processed evidence, or a bystander who watched the crime take place.
Physical evidence is deemed admissible when it pertains to the case and a clear chain of custody can be established, with people demonstrating that the evidence is authentic and that it has been protected to ensure that the integrity is retained. Evidence which is mishandled or obtained by illegal means is not admissible evidence, which can be become a big problem in a legal case; there may be a situation in which evidence is very relevant and important, but it cannot be discussed in court due to the fact that it was not handled correctly.
Judges may also consider the issue of “undue prejudice” when evaluating evidence to determine whether or not it is admissible. If the presentation of evidence would create an unreasonable bias, the people presenting the evidence may be obliged to withdraw or adjust it. For instance, in a violent crime, a graphic description or images of the scene might not be permitted due to concerns about undue prejudice.
Concerns about admissible evidence are very important to the people who investigate crimes. They want to make sure that the evidence they handle is carefully documented and secured so that it can be used in court. They are especially careful when they suspect that they may be creating a precedent. When DNA evidence was first used in court, for example, it was accompanied with ample expert testimony, meticulous documentation, and a clear discussion of the techniques used to collect and analyze DNA samples, demonstrating that the evidence was admissible and laying the groundwork for the future use of DNA as admissible evidence in legal cases.