Best evidence rule

Best evidence rule

The best evidence rule is a common law rule of evidence which can be traced back at least as far as the 18th century. In Omychund v Barker (1745) 1 Atk, 21, 49; 26 ER 15, 33, Lord Harwicke stated that no evidence was admissible unless it was "the best that the nature of the case will allow". The general rule is that secondary evidence, such as a copy or facsimile, will be not admissible if an original document is available.

The rationale for the best evidence rule can be understood from the context in which it arose: in the eighteenth century a copy was usually made by hand by a clerk (or even a litigant). The best evidence rule was predicated on the assumption that, if the original was not produced, there was a significant chance of error or fraud in relying on such a copy.

In the age of digital facsimiles, etc. the rule is more difficult to justify. The likelihood of actual error (as opposed to mere illegibility) through copying is slight. The balance of convenience favours avoiding needless effort and delay where there is no dispute about the fairness and adequacy of a digital facsimile. Further, it is by no means clear what the 'original' of an electronic communication such as an e-mail actually is: as a great many electronic 'copies' of a message might come into existence from creation to receipt.

The best evidence rule is also thought to be the basis for the rule precluding the admissibility of hearsay evidence, although the two rules are now quite distinct.

United States

In the United States the rule has been codified in the Federal Rules of Evidence as rule 1002:

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.

The rule requires that when writings are introduced as evidence in a trial, the original writing must be produced as the "best evidence". In Federal practice, however, any exact copies of the original carry the same legal weight as the original unless their authenticity is in question.

The term "writing" has been liberally interpreted to include photographs, x-rays, and films. Note that for photographs and film, this could be construed to mean negatives, not prints, as they are the true 'original'.

The rule applies in two situations:

  • Where the terms of the writing are legally dispositive in the issue at bar (not collateral documents or issues).
  • Where the witness's sole knowledge of a fact comes from having read it in the document.

There is an exception. If the original document is unavailable for reasons other than serious misconduct of the proponent, secondary sources of evidence (such as oral testimony) can be used in place of the original.

Currently, both California law and the Federal rules allow the use of mechanically produced duplicates unless a party has raised a genuine question about the accuracy of the copy or can show that its use would be unfair.

England and Wales

Blackstone's Criminal Practice states that:
The best evidence rule, which was used in the 18th and early 19th centuries as an exclusionary principle, i.e. to prevent the admission of certain evidence where better evidence was available, is now all but defunct.
Lord Denning MR has stated:
The old rule, that a party must produce the best evidence that the nature of the case will allow, and that any less good evidence is to be excluded, has gone by the board long ago. The only remaining instance of it is that, if an original document is available on one’s hands, one must produce it; that one cannot give secondary evidence by producing a copy. Nowadays we do not confine ourselves to the best evidence. We admit all relevant evidence. The goodness or badness of it goes only to weight, and not to admissibility.


Canada inherits the best evidence rule from the Common Law of Great Britain. For example, the Immigration and Refugee Board provides the following definition

The law does not permit a man to give evidence which from its very nature shows that there is better evidence within his reach, which he does not produce.

citing Doe d. Gilbert v. Ross (1840) 7 M. & W. 102, 151 E.R. 696 (Exch.) as the source. This page then provides the clarification that

While this rule originally applied to all evidence, it has been restricted in its application to documentary evidence: if the original document is available, it must be produced. Otherwise, all relevant evidence is admitted into evidence, and whether it is the best evidence available, simply goes to weight.

The documentary aspect of best evidence is taken up in the Canada Evidence Act. PIPEDA modified this act to include provisions for electronic best evidence, viz,

Application of best evidence rule — electronic documents

31.2 (1) The best evidence rule in respect of an electronic document is satisfied

(a) on proof of the integrity of the electronic documents system by or in which the electronic document was recorded or stored; or

(b) if an evidentiary presumption established under section 31.4 applies.

Presumptions regarding secure electronic signatures

31.4 The Governor in Council may make regulations establishing evidentiary presumptions in relation to electronic documents signed with secure electronic signatures, including regulations respecting

(a) the association of secure electronic signatures with persons; and

(b) the integrity of information contained in electronic documents signed with secure electronic signatures.

Refer to Secure electronic signature and digital signature for more information.


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