Legal evidence is material that can be used in pursuit of a legal case. The evidence is brought to court for the purpose of demonstrating or refuting a point related to a case. There are many different types of evidence, and legal systems in most nations have strict rules regarding admissibility of evidence, evidence collection, and related matters. The goal of carefully regulating evidence is to ensure that only evidence that is valid and relevant is brought to court.
A classic example of legal evidence is testimonial evidence from witnesses, which can include direct evidence about an event someone saw firsthand, as well as indirect evidence, like a professional opinion. Witnesses can make unreliable evidence because they can have imperfect memories or may have been influenced by things that occurred between the event and the trial. Attorneys are careful about how they question and interact with witnesses to ensure that the evidence provided will be of the highest quality possible. Rules of legal evidence state that the evidence must be relevant to the case and it must be presented in its original form unless there is a compelling reason not to do so. Copies of evidence are not admitted due to concerns about tampering. An exception might be a case where evidence is too fragile or has been destroyed during testing, in which case a copied version may be accepted, as long as it is clearly labeled as such.