In most respects the general rules of evidence are the same in civil and criminal causes. One of the general rules is, the best evidence must be produced or its absence accounted for before secondary evidence is permissible. Therefore the contents of a letter or other writing cannot be shown by oral testimony or by a copy until it is first shown that the original cannot be produced, the original letter or writing being the best evidence.1

So if it becomes necessary to prove a former conviction or acquittal of the accused, the record, or a certified copy thereof where authorized by statute instead of the original, is the only competent evidence of such former conviction or acquittal.2

When a certified copy of any record is produced for the purpose of introducing it in evidence, it must be attested in proper manner as required by statute or act of congress.3

Exemplification of judgments of record of other states, to be admissible under the act of congress, must be attested by the clerk under the seal of the court, with the certificate of the presiding judge that the attestation of the clerk is in due form.4