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.

Shanklin v. Norfolk Southern Railway Co., 369 F.3d 978, 990 (6th Cir. 2004) (holding, in plaintiff wife's wrongful death action against defendant railroad company, that the trial court properly admitted the officer's video deposition....Although the statement of a "speaking agent" can be imputed to an employee's employer or an agent's principal and can be a vicarious admission that is exempt from the prohibition against hearsay, such an employee or agent must in fact have been authorized by the employer or principal to speak on behalf of the employer or principal. This is necessary if the basis of the imputation of the employee's or agent's statement to the employer or principal is that the employee or agent was a "speaking agent."

Cf. United States v. McClesky, 228 F.3d 640, 644-645 (6th Cir. 2000) (reversing convictions for drug related offenses because the trial court erroneously admitted accomplice's statement [which lacked sufficient indicia of....A statement qualifies as a statement against interest for purposes of the hearsay exception for statements against interest only if the statement, at the time the declarant made it, was so contrary to the declarant's interest that a reasonable person in the declarant's position would not have made if the declarant had believed the statement to be untrue.

Cf. Commissioner of Internal Revenue v. Kilpatrick, 227 F.2d 240, 243 (5th Cir. 1955) (holding that the evidence of petitioner taxpayer's nolo contendere convictions of tax evasion was admissible for impeachment purposes because the "Tax Court....Federal Rule of Evidence 410 or a comparable State rule bars the use of a nolo contendere plea (no contest plea) as evidence in any proceeding against the defendant who entered this plea.