The purpose of the opening statement is to to provide a trier of fact with a non-argumentative preview of the case and the evidence.

United States v. Owens, 484 U.S. 554, pin? (1988).For purposes of the hearsay exceptions created by Federal Rule of Evidence 804 or a comparable State rule, a declarant is "unavailable" within the meaning of Rule 804(a) or a comparable State rule if the declarant testifies to a lack of memory of the subject matter of the declarant's statement; but a declarant is not "unavailable" if such claim of lack of memory is due to the procurement or wrongdoing of the proponent of a statement for the purpose of preventing the witness from attending or testifying.

United States v. Console, 13 F.3d 641, 656-657 (3d Cir. 1993) (upholding trial court's admission of the Accident Book as a business record because the qualified witness testified that "through her work, she became....The hearsay exception for "business records" created by Federal Rule of Evidence 803(6) or a comparable State rule applies only (i) the record is based on the personal knowledge of an entrant with a business duty to record the event or other such matter or (ii) if the record of the event is based on the personal knowledge of a person who had a business duty to transmit the information about the event or other matter to the person or persons who made the record and had a business duty to do so. A person has a "business duty" if the person has a duty to an organization by reason of law, contract, employment relationship, or other such matter to record or report an event, condition, opinion, or other matter to which the business records exception to the hearsay rule may apply.

Fed. R. Evid. 804(b)(1) advisory committee's note ("As a further assurance of fairness in thrusting upon a party the prior handling of the witness, the common law also insisted upon identity of parties, deviating only to the extent of allowing substitution of successors in a narrowly construed privity. Mutuality as an aspect of identity is...The hearsay exception for prior testimony can apply in a criminal trial or proceeding against a defendant even if the prosecuting party and offeror in the prior trial or proceeding was a different party and offeror (e.g., a different governmental unit).