Rule 703 embodies a tension between letting experts do their jobs of gathering information and forming opinions and limiting disclosure of what information the experts gathered.
Experts who are good go to lots and lots of sources before they reach a conclusion. And this is encouraged under Rule 703, as long as those sources are ones “experts in the particular field would reasonably rely on those kinds of facts or data in forming an opinion on the subject…” Rule 703, Fed.R.Evid.
So in part this is a ‘trust the expert’ rule. Experts help educate judges as to what sources of information are reasonably relied upon in the particular field; and judges then decide whether to accept that claim. Judges do so under their Rule 104(a) decision-making authority.
But what an expert may rely upon is different from what an expert may repeat in court when explaining the opinion. Here is where Rule 703’s language, and the Amendment to the Rule in 2000, becomes important. 703 first provides language about reliance:
If experts in the particular field would reasonably rely on those kinds of facts or data in forming an opinion on the subject, they need not be admissible for the opinion to be admitted.
Rule 703 (emphasis added). In other words, in most instances, the side opposing an expert can’t object and seek to exclude an opinion because the expert used inadmissible evidence to reach the conclusion. The opinion is still admissible. Thus, the opinion that “the patient suffered from a form of cancer that could have been treated” or “the conditions in the store were unsafe for young children” is admissible even if the expert relied to some extent on evidence that itself is not admissible at trial.
[The rare instance in which the entire opinion will be excluded occurs when the only information relied upon is inadmissible hearsay and that inadmissible evidence is the sole proof of the underlying fact. For example, in Turner v. Burlington N. Santa Fe R.R., 338 F.3d 1058, 1060 (9th Cir. 2003) an arson investigator was prepared to opine that a fire was intentionally started based upon a report that debris from the fire had gasoline in it. The lab analysis however was not admitted into the record and thus was inadmissible hearsay. The exclusion of the expert opinion was upheld because the opinion had relevance only if the lab report was true.]
What is an example of evidence that may be relied upon but might not be admissible at trial? Suppose a psychologist was trying to learn whether a person had a severe learning disability. The expert might conduct tests on the subject, and because the expert personally administered those tests the expert would have personal knowledge and could describe them. But the same expert might also have interviewed former teachers and relatives of the subject. What each interviewee told the expert is information of a type “reasonably relied upon” in the field of psychology, but each statement is inadmissible hearsay. The overall opinion – that the person did or did not have a disability – would be permissible even though it was based in part on hearsay interviews that themselves would be inadmissible at a trial. [Of course, if the teachers and relatives came to court and testified to their observations, there would be no inadmissible evidence.]
703 also addresses whether the trier of fact – for all intents and purposes the jury – may hear/read the inadmissible evidence. It provides that
if the facts or data would otherwise be inadmissible, the proponent of the opinion may disclose them to the jury only if their probative value in helping the jury evaluate the opinion substantially outweighs their prejudicial effect.
Stated more simply, the expert may give the opinion but not the inadmissible evidence behind it unless giving the jury that information is necessary to understand how the expert reached the conclusion and if doing so substantially outweighs the prejudice of letting the jury hear or read assertions that cannot be cross-examined or otherwise tested for truth and accuracy.
The NOTE to the 2000 Amendment to Rule 703 makes this clear – “Rule 703 has been amended to emphasize that when an expert reasonably relies on inadmissible information to form an opinion or inference, the underlying information is not admissible simply because the opinion or inference is admitted.”
So how does is this intended to work? Using the psychologist example above, the expert may testify as follows:
Q: Did you form an opinion as to whether X has a learning disability?
A: Yes.
Q: And does X have that disability?
A: Yes. A severe one.
Q: Tell us what information you relied on to form that opinion?
A: I administered two intelligence tests, and the results were…
Q: Is that the only information you relied on?
A: No.
Q: What else did you consider?
A: I interviewed teachers and relatives of X.
Q: And based on all of those sources, the two tests and the interviews, what is the conclusion?
A: X has a severe learning disability.
This examination conforms with Rule 703. The inadmissible evidence may be disclosed only if a judge determines that the jury must hear/see what information relied on to make the direct examination and opinion comprehensible, and then only with a jury instruction that the evidence is not being introduced for the jury to treat as a true fact in the case but only to explain that this information is what this expert used for formulating the opinion.
This would look like the following:
Q: What else did you consider?
A: I interviewed teachers and relatives of X.
Q: What did they tell you?
BY THE COURT: Members of the jury, what other people told the psychologist is what we call hearsay. There is no proof that what they said is in fact accurate – it may be, it may not be, we just don’t know. They are not here to be asked questions. So you can’t assume that what they said is true – but you may hear it now just to understand what information the psychologist relied on and how the psychologist made this conclusion. Now, you may answer the question.
A: The teachers told me about difficulties with reading and remembering, and relatives told me stories about how the subject often could not perform basic tasks like addition or subtraction.
This same approach will apply in a state such as Pennsylvania, where the evidence rules require disclosure of all facts the expert relied upon but with the cautionary instruction.
Of course – and at its own risk – the party opposing the expert may force disclosure of the inadmissible evidence under Rule 705, which states that “the expert may be required to disclose those facts or data on cross-examination…” But until that happens, effective lawyering in the face of expert testimony requires ensuring the application of Rule 703 and restricting ‘backdoor hearsay.’