Idaho Code § 9-403: Notice to produce writing — Proof upon failure to produce — When notice not necessary.

If the writing be in the custody of the adverse party, he must first have reasonable notice to produce it. If he then fail to do so, the contents of the writing may be proved as in case of its loss. But the notice to produce it is not necessary where the writing is itself a notice, or where it has been wrongfully obtained or withheld by the adverse party.