I've written on here about impeachment, and I've written about hearsay. A sort of hybrid issue can appear on the test in which a question arises as to whether a hearsay declarant can be impeached.
In other words, when a statement that would otherwise be inadmissible hearsay is admitted because of an exemption or an exception, the person who made that statement functions as a sort of witness in the case. Even though the hearsay declarant isn't present at the trial, the jury will now consider the statement just as if the person had made the statement while testifying.
As such, it only makes sense that the credibility of that hearsay declarant may be attacked, and attacking the credibility of any witness is the crux of impeachment. Any method for impeaching any witness will apply to impeaching a hearsay declarant. Though there is an important distinction to keep in mind.
You might recall that one method to impeach a witness (including a hearsay declarant) is by a prior inconsistent statement. Generally, an essential component of the foundation for offering a prior inconsistent statement to impeach a witness is to give that witness an opportunity to explain or deny the prior inconsistent statement. This foundational requirement can be modified under circumstances where justice requires, though that would very much be the exception rather than the rule.
But that requirement does not apply when impeaching a hearsay declarant on a prior inconsistent statement. The hearsay declarant need not be given an opportunity to explain or deny the prior inconsistent statement.
So, the two takeaways here are that hearsay declarants should be treated, for the most part, as any witness is treated. Since the jury will consider their statements, it is the right of an adverse party to call into question the credibility of those statements. But if the method of impeaching a hearsay declarant is to show a prior inconsistent statement (inconsistent with the statement admitted as a hearsay exception or exemption) the safeguard of allowing the witness to explain or deny the prior inconsistent statement does not apply.
