The Pennsylvania Rules of Evidence 804(b)(3) provides for an exception to the general hearsay rule. An oral or written statement of fact which a person knew to be against his own pecuniary, proprietary or penal interest when made is excepted from the hearsay rule, provided that the declarant had personal knowledge of the fact and is now unavailable to testify as a witness.
Statements against interest by any unavailable declarant are admissible as a hearsay exception because their trustworthiness is safeguarded by the improbability that a declarant would fabricate a statement that is contrary to his own interest. It is founded "on the commonsense notion that reasonable people, even reasonable people who are not especially honest, tend not to make self-inculpatory statements unless they believe them to be true." Commonwealth v. Colon, 461 Pa. 577 (1975).
The proponent of the evidence bears the burden of showing that the declarant is unavailable. Unavailability based on Fifth Amendment privilege satisfies the rule.
Your Bucks County criminal lawyer should be ready to pounce on two particular points when the government tries to make a statement admissible under this exception. First, they should argue whether the government knows that a declarant is unavailable to testify.
The second way is to find out if the person/declarant actually had personal knowledge.