A statement made by a person subjected to psychiatric or psychological examination or treatment pursuant to sections 18-211, 18-212 or 19-2522, Idaho Code, for the purposes of such examination or treatment shall not be admissible in evidence in any criminal proceeding against him on any issue other than the defendant's ability to assist counsel at trial or to form any specific intent which is an element of the crime charged, except that such statements of a defendant to a psychiatrist or psychologist as are relevant for impeachment purposes may be received subject to the usual rules of evidence governing matters of impeachment.
Idaho Code § 18-215