Hypothetical: It is a toxic exposure personal injury trial and plaintiff's causation expert is testifying. She opines that plaintiff's exposure to defendant's chemical product caused plaintiff's injury. The next question: "And doctor, in your work in this case, you read the report of the blue ribbon expert panel of the World Health Organization, and they agree with you: The chemical can cause plaintiff's injury, correct?"
An attorney barks, "objection, hearsay!"
The correct ruling? Not enough information to tell. If the expert is on direct, "sustained"; if it's cross, "overruled."
Here we review the basics involving hearsay and experts including the game changer California Supreme Court decision, People v. Sanchez, 63 Cal. 4th 665 (2016). The key points: (1) The rules are different on direct vs. cross; and (2) the rules on direct have changed in a big way.
Experts and Hearsay, on Direct
Rule One: An expert may rely upon hearsay in forming an opinion. Evidence Code Section 801 reads in part: "If a witness is testifying as an expert, his testimony in the form of an opinion is limited to such opinion as is: ... (b) based on matter ... made known to the witness before the hearing, whether or not admissible, that is of a type that reasonably may be relied upon by an expert in forming an opinion upon the subject to which his testimony relates." (Emphasis supplied.)
This is wholly uncontroversial: Experts, and the rest of us, rely on inadmissible trade hearsay all the time. A treating physician is informed in her opinions on proper treatment by, say, the pathologist's written report; an engineer's reconstruction of the accident is informed by, say, a police report recording the length of tire skid marks. Hearsay to be sure, but of the type that experts in that field reasonably and conventionally rely upon.
The point to note: Relying on hearsay and publishing that hearsay on direct are two different things.
Rule Two: The expert may state on direct the "matter" on which her opinion is based. Evidence Code Section 802. A good rule: A jury evaluating the convincing force of an expert opinion should at least know what the expert read. Is the expert's opinion based on a peer-reviewed study from the physics department at MIT or three horoscopes? It matters. But now things get sticky.
Rule Three: "While an expert may state on direct examination the matters on which he relied in forming his opinion, he may not testify as to the details of such matters if they are otherwise inadmissible. The rule rests on the rationale that while an expert may give reasons on direct examination for his opinions, including the matters he considered in forming them, he may not under the guise of reasons bring before the jury incompetent hearsay evidence." People v. Coleman, 38 Cal. 3d 69, 92 (1985) (citations omitted, overruled by Sanchez, 63 Cal. 4th at 686 n.13).
If you stopped reading at this point, you would be badly misled because not much of Rule Three still exists after Sanchez. But some does, meaning we need to know the older rule. So where's the line between permissibly stating "matter" on which the opinion is based and impermissibly stating "details"?
Historically, this was a matter of judicial discretion. The classic expression is in Continental Airlines, Inc. v. McDonnell Douglas Corp., 216 Cal. App. 3d 397, 415 (1989): "[W]hile an expert may rely on inadmissible hearsay in forming his or her opinion and may state on direct examination the matters on which he or she relied, the expert may not testify as to the details of those matters if they are otherwise inadmissible." (Citations omitted, emphasis supplied.)
Also, courts sometimes found that the expert's stating on direct the details of out-of-court statements on which she relied wasn't hearsay at all because they were not being received for their truth. As the Coleman court wrote, "[o]rdinarily, the use of a limiting instruction[,] that matters on which an expert based his opinion are admitted only to show the basis of the opinion and not for the truth of the matter[,] cures any hearsay problem involved, but in aggravated situations, where hearsay evidence is recited in detail, a limiting instruction may not remedy the problem." 38 Cal. 3d at 92 (emphasis supplied).
Rule Four: Unlearn most of Rule Three. Post-Sanchez, an expert, on direct, may not testify about case specific facts on which the expert relied if such information is otherwise inadmissible hearsay. Thus, the doctor can't say what the pathologist's report of plaintiff's tissue showed; the accident recon can't say how long the skid mark was based on the police report - unless those facts are already in evidence. Can they still rely on such hearsay information? Yes. Tell the jury even if not too detailed? No.
Where Sanchez applies, courts no longer draw lines between "matter relied on" and "details"; courts no longer give limiting instructions that such information is not being received for their truth. Justice Carol Corrigan's clear summary: "What an expert cannot do is relate as true case-specific facts asserted in hearsay statements, unless they are independently proven by competent evidence or are covered by a hearsay exception." Sanchez, 63 Cal. 4th at 686.
Rule Five: Thus, expert reliance hearsay is either case specific or general background. The Sanchez rule only applies to the case specific variant. Case specific facts are those "relating to the particular events and participants alleged to have been involved in the case being tried." Id. at 676. Thus, a criminologist's identification on direct examination of an illicit pharmaceutical in the defendant's possession based upon the criminologist's comparison of them to an "Ident-A-Drug" website was an expert's relying on "case specific" hearsay. This was impermissible. People v. Stamps, 3 Cal. App. 5th 988 (2016). So, too, in adjudicating defendant's status as a sexually violent predator, the plaintiff's expert's testimony on direct about defendant's "qualifying offenses" from probation reports were case specific hearsay and should not have been admitted under Sanchez. People v. Burroughs, 6 Cal. App. 5th 378 (2016).
What about general background type hearsay? The Continental Airlines not-too-detailed rule still appears to apply. The Stamps court commented: "If the hearsay relied upon by the expert is not case-specific, as we read Sanchez, the evidence is still admitted for its truth and is therefore hearsay, but we tolerate its admission due to the latitude we accord experts, as a matter of practicality, in explaining the basis for their opinions. Where general background hearsay is concerned, the expert may testify about it so long as it is reliable and of a type generally relied upon by experts in the field, again subject to the court's gatekeeping duty." (Citations omitted.)
The bottom line: Trial counsel should not plan on getting an important piece of case specific hearsay evidence before the jury through an expert on direct.
Experts and Hearsay, On Cross
On cross of an expert, the hearsay rules are entirely different. Indeed, often in a good expert cross, counsel will state scads of hearsay usually in the form of writings that contradict the expert's opinions. This is permissible under Evidence Code Section 721(b), a powerful tool. That section permits an expert to be cross-examined "in regard to the content or tenor of any scientific, technical or professional text, treatise, journal or similar publication." Often the cross consists of little more than counsel reading the impeaching hearsay sound bite from a publication in the expert's file followed by "did I read that correctly?" or "you read that as part of your work in this case, right?"
But before counsel on cross may so proceed, there is foundation to establish: (a) That the expert "referred to, considered or relied" upon the publication in arriving at or forming her opinion; (b) that the publication is already admitted in evidence; or (c) that the publication has been established as a reliable authority by testimony of the witness or by other expert testimony or by judicial notice. Typically, counsel will insist an adverse expert to produce at her deposition all materials she "referred to considered or relied upon." Then, counsel pores through such materials selecting impeaching sound bites for trial.
Experts can try inoculate themselves from such treatment by willfully blinding themselves to a particular publication. "So doctor, you did not consider Darwin's publication on the origin of species?" "Nope, never heard of it." But that the expert may still be cross-examined with that publication if another expert has testified that the publication is a reliable authority. This can set up a timing issue: Defendant's experts will not have testified in trial by the time plaintiff's experts will be cross-examined, and for that reason the defense expert will need to have expressed the opinion in deposition that the writing is reliable authority. Likewise, a plaintiff planning for a defense expert's cross later will need to establish the publication as reliable authority, and while that can be done at trial, it again is an opinion that should be expressed in pretrial expert discovery. Kennemur v. State of California, 133 Cal. App. 3d 907 (1982).