The best evidence rule can be traced back to 18th-century Great Britain and continues to be part of many legal systems, including the United States'. The original purpose of the rule was to prevent altered evidence, whether intentionally altered or accidentally altered, from being admitted in a court of law as evidence. Although the best evidence rule continues to be a part of the current United States federal Rules of Evidence, the original purpose has become somewhat obsolete and its practical application is complicated in the electronic age.
Under the Federal Rules of Evidence, Rule 1002 states, "To prove the content of a writing, recording, or photograph, the original writing, recording, or photograph is required, except as otherwise provided in these rules or by Act of Congress." In the United States, this is the codification of the best evidence rule. Quite simply, the rule requires that an original must be produced unless one of a limited number of exceptions to the rule applies, allowing a duplicate to be used.
The best evidence rule was originally needed because, prior to the digital age, copies of documents were made by hand. Clearly, errors were commonly made. In addition, the person who made the copy was often the same person who wished to admit the document into court as evidence. As such, intentional "errors" were often made when the error was to the benefit of the person making the copy. The legal solution to this problem was to require an original to be produced when a party wished to admit a document into court as evidence.
The original justification for the best evidence rule does not exist to the extent that it once did. Most copies are made by a facsimile machine that cannot make errors in the same way that a person copying the document by hand would. Copies of video, recording or photos are also not subject to the same concerns about tampering that an 18th century document once was.
While the purpose of the best evidence rule has become more difficult to justify, applying the rule has also become complicated. With the vast majority of communication now being accomplished through electronic means and the average person regularly using video and sound to record events, determining that a piece of evidence is the original has become time-consuming and expensive. Verifying that a video or sound recording has not been tampered with can require an expert analysis, which takes a considerable amount of time and money. E-mail or text messages are equally difficult to authenticate as originals, yet they comprise the vast majority of communication in the digital world.