Best evidence

An original document or object offered as proof of a fact in a lawsuit as opposed to a photocopy of, or other substitute for, the item or the testimony of a witness describing it.

Best evidence, also known as primary evidence, usually denotes an original writing, which is considered the most reliable proof of its existence and its contents. If it is available to, and obtainable by, a party, it must be offered into evidence at a trial. Best evidence is distinguishable from secondary evidence, a reproduction of an original or testimony establishing its existence, which will be admissible as proof only if the best evidence cannot be obtained, and ensuring no fault of the party seeking to present it.

The principle that the best available evidence must be presented as proof in a lawsuit is embodied in the best-evidence rule.

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BEST EVIDENCE. Means the best evidence of which the nature of the case admits, not the highest or strongest evidence which the nature of the thing to be proved admits of: e. g. a copy of a deed is not the best evidence; the deed itself is better. Gilb. Ev. 15; 3 Campb.. 236; 2 Starkey, 473 2 Campb. 605; 1 Esp. 127.
     2. The rule requiring the best evidence to be produced, is to be understood of the best legal evidence. 2 Serg. & R. 34; 3 Bl. Com. 368, note 10, by Christian. It is relaxed in some cases, as, e. g. where the words or the act of the opposite party avow the fact to be proved. A tavern keeper's sign avows his occupation; taking of tithes avows the clerical character; so, addressing one as The Reverend T. S." 2 Serg. & R. 440 1 Saund. on Plead. & Evid. 49.