You describe Agent Robillard's testimony as involving "an implied prior representation of which the declarant disclaims present knowledge," on the grounds that his qualification as an expert implied that "he had a valid reason for reaching that conclusion at the time of his investigation." But the question reserved in Green involved an express prior representation specifically introduced by
the prosecution as substantive evidence. I see nothing in our cases that would justify embarking on the difficult and questionable enterprise of deciding when there has been an implied representation. In any event, in this case, Agent Robillard openly admitted at voir dire that he could not recall which reason was the basis for his conclusion. App. to Brief in Opposition A-1-A-2. That admission would seem to preclude finding any implied representation. Thus, unless the Confrontation Clause required the trial court to refuse to qualify Robillard as an expert witness because of his lapse of memory, your analysis would not affect the resolution of this case.
O'Connor, S.D. Correspondence from O'Connor to Stevens, Delaware v. Fensterer, 474 U.S. 15 (1985). Box 367, Harry A. Blackmun Papers, Manuscript Division, Library of Congress, Washington, D.C.