Best Evidence Rule

The best evidence rule is a rule of evidence that requires that original documents be used to prove the contents of writing, photograph or the like unless it is unavailable. If unavailable, then a duplicate may be used under the current evidence rules. For example, if during trial, a witness for the prosecution testifies about something solely based on her memory of what was in a particular document, the defense attorney can object to her testimony based on the best evidence rule, arguing that the document itself should be used as evidence, not her testimony.