A witness's testimony is evaluated on the basis of four factors: perception, memory, narration, and sincerity. In order that the testimony can be properly considered in the light of these factors, the testimony should comply with three conditions. The witness should testify (1) under oath, (2) in the presence of the trier of fact, and (3) be subjected to cross-examination. Past experience as well as common sense indicate that some testimony which does not conform to these three conditions may be more valuable than testimony that does. The four factors may, in some instances, be present in the absence of compliance with the three aforementioned conditions. The solution that the common law developed over a period of time was a general rule against hearsay which permitted exceptions which furnished guarantees of trustworthiness and reliability.
The hearsay provisions of the uniform rules retain the common law scheme. The traditional common law hearsay exceptions have been retained in Rules 803 and 804. Rule 803 concerns itself with situations where availability of the declarant is immaterial. Rule 804 pertains to exceptions which are usable only where the declarant is unavailable. The concluding provisions of both Rule 803 and 804 (Rule 803(24) and Rule 804(b)(5) respectively) allow for the use of hearsay statements which do not fall within the recognized exceptions, when the guarantees of trustworthiness and necessity are present. These two provisions are a recognition that the law is not stagnant; they are designed to encourage the development of this area of the law.