Evidence can become stale, obsolete, or no longer provable. Suppose there is a witness to a car accident. Witness testimony is far more credible within two years of the incident than ten years.According to The Neuroscience of Memory: Implications for the Courtroom, memories become less detailed over time, retaining only the generalized information. If a car accident injury claim is filed ten years after the accident, the witness is unlikely to recall any pertinent collision details.