This is the property of the Daily Journal Corporation and fully protected by copyright. It is made available only to Daily Journal subscribers for personal or collaborative purposes and may not be distributed, reproduced, modified, stored or transferred without written permission. Please click "Reprint" to order presentation-ready copies to distribute to clients or use in commercial marketing materials or for permission to post on a website. and copyright (showing year of publication) at the bottom.

self-study / Evidence

Feb. 25, 2022

The Evidence Slayer: Evidence Code Section 721(b)

Spring Street Courthouse

Lawrence P. Riff

Site Judge, Los Angeles County Superior Court

Evidence Code Section 721(b): The Expert Slayer

You have heard Professor John Wigmore's dictum a hundred times: "Cross-examination is the greatest legal engine ever invented for the discovery of truth." Wigmore, 5 "Evidence" Section 1367, at 29 (3d ed. Little, Brown & Co. 1940).

If only t'were that simple. It's not.

A tight, controlled, well-executed cross-examination is the triple axel of trial practice. Many a trial lawyer has wiped out on the ice in the midst of cross-examination. Hardest of all? Cross-examining an experienced, self-possessed, professional expert witness.

Expert witnesses are, well, witnesses and thus all the modes of impeaching cross-examination are theoretically available, such as the prior inconsistent statement, conviction of an act of moral turpitude, and garden-variety bias. But experts are often selected on account of their impressive credentials, fine reputations and unflappable battle-hardened exteriors. There is usually little good to come of those pedestrian modes of impeachment.

To do the job right, one will need to confront the expert on her own turf: the actual subject matter of her opinion. This is difficult and perilous. If poorly done, the cross-examination provides the expert with yet another chance to explain her opinion, reinforcing her prestige and ignominiously "schooling" the cross-examiner with the factfinder as her audience: "No counsel, let me explain again why the premise of your question is hopelessly wrong." Ouch! Many lawyers elect instead to go with, "No questions, your Honor" -- while studiously effecting a dismissive tone of, "why would I spend another minute of this court's time with this wrongheaded chump?" This method of "confronting" the opposing expert is called "magical thinking" and is based on the hope the factfinder might, somehow, forget the expert's devastating direct testimony.

There is a better way: Unleash Evidence Code Section 721(b) -- aka, the "expert slayer."

Section 721(b) allows the cross-examiner to show, with ease, that the witness is willfully ignoring important, authoritative and reliable material that runs counter to the opinion she has just offered. Exposing this sleight of hand is done in one of two ways: (1) by demonstrating that the expert has in fact considered the contrary information but is pretending it does not exist; or (2) better yet, that she has willfully blinded herself to such materials to avoid having to explain them away. Demonstrating either permits the argument that the expert, who strives to be seen as the court's neutral "science advisor," is in fact an intellectually dishonest partisan shill, not worthy of belief.

Section 721(b) provides: "If a witness testifying as an expert testifies in the form of an opinion, he or she may not be cross-examined in regard to the content or tenor of any scientific, technical, or professional text, treatise, journal, or similar publication unless any of the following occurs: (1) The witness referred to, considered, or relied upon such publication in arriving at or forming his or her opinion. (2) The publication has been admitted in evidence. (3) The publication has been established as a reliable authority by the testimony or admission of the witness or by other expert testimony or by judicial notice. If admitted, relevant portions of the publication may be read into evidence but may not be received as exhibits." Note well: This is a "may not unless" formulation. That means the cross-examination will require some advance planning.

Let us illustrate with a hypothetical. (To illustrate a later point, this hypothetical posits an intellectually dishonest plaintiff's expert. But to be sure, this discussion applies to intellectually dishonest defense experts, too.) Let's say a key issue in a product liability personal injury case is whether a specific chemical compound found in the product, chemical X, caused the plaintiff's pancreatic cancer. The plaintiff's expert has formed the opinion, which she holds to a reasonable degree of medical probability, that yes, chemical X caused plaintiff's cancer. Now the expert must defend the reliable basis for that opinion. Long gone are the days of the bald ipse dixit ("because I say so and look at my impressive resume"); admissible expert opinions must now have a sound, reliable basis. Sargon Enterprises, Inc. v. University of Southern California, 55 Cal. 4th 747 (2012) (trial court properly exercises its "gatekeeper" role on expert opinion testimony by ensuring such opinions have a reliable basis.).

This means the expert must compile a file of reliable materials upon which the opinion is based. The file will include case-specific information (e.g., medical records and exposure information) and non-case-specific materials from the world's scientific literature investigating the causal relationship between the chemical X and the particular form of cancer. These latter materials may consist of animal toxicology studies, human epidemiology studies, and learned treatises from seemingly authoritative bodies such as the U.S. Environmental Protection Agency of the World Health Organization's International Agency for Research on Cancer, known as IARC.

Let us further assume that IARC published in 2021 a comprehensive toxicology review of chemical X which concludes with this statement: "Based on our comprehensive review of all the relevant animal and human studies performed to date, we cannot say that chemical X has been shown to cause pancreatic cancer in humans." Last, let us assume that the expert actually placed the IARC review article in her file in this case.

The cross-examination can sound like this: "Doctor, you placed the IARC comprehensive review in your file -- may we assume that you read and considered it as part of your work in this case?"

The answer must be "yes" or the expert looks pretty silly.

If the answer is "no," now it's like shooting fish in a barrel: "Really? Then why did you put it in your file, doctor? In order to make it seem like you did more work than you actually did?"

But with the expected affirmative answer to this question -- "Yes, I read and considered it" -- now the defense-helpful summary statement may be read to the jury as part of the cross-examination because Section 721(b) requires only the foundation that the witness "considered" the publication.

The next question sounds like: "So, will you confirm for us that when you read and considered the document, you saw IARC's ultimate conclusion, namely 'based on our comprehensive review of all the relevant animal and human studies performed to date, we cannot say that chemical X has been shown to cause pancreatic cancer in humans'?"

Note the question only asks only "Did you see?" -- not, "Why did you discount it?" or "Don't you agree?" The answer to the "Did you see?" again will be in the affirmative.

Now, cross-examiner: Leave it alone! Move on! Don't ask anything else about that point! Let the proponent of the witness ask that defensive-sounding question on re-direct: "Well, gee, doctor, how come your opinion varies with IARC's?" One way or the other, the factfinder is now aware that this very authoritative-sounding body has a different opinion on the key point and there is hay to be made at closing argument.

What if the cagey expert witness, for exactly that reason, did not include the IARC review in her file? This is a case of the witness willfully blinding herself to materials that she does not want to have to explain away. The cross-examiner could try this tack: "Doctor, you are aware, are you not, that the International Agency for Research on Cancer published a comprehensive review of chemical X just last year?" If the witness says, "Nope, never heard of it or IARC either for that matter counsel," then the cross-examination is done under subsections (1) and (2) of Section 721(b) because the witness did not reference, consider or rely on the IARC review, nor is the review in evidence.

But all is not lost: There is still subsection (3): the cross-examiner may still cross-examine on the IARC review and its helpful statement if counsel can establish the publication is a "reliable authority" even if the witness never considered it. Paige v. Safeway, Inc., 2022 DJDAR 1488 (Cal. App. 1st Dist. Feb. 10, 2022) (trial court erred in precluding cross-examination of a defense expert on an ASTM engineering standard where the expert opined that the standard was reliable authority but he did not consider it in forming his opinion); People v. Loker, 44 Cal. 4th 691, 737 (2008) (cross-examination of defense expert in capital case on propositions from a textbook on hyperactive children was proper where expert agreed the textbook was the leading authority in the field).

It is possible that the witness will concede the foundational point: "Doctor, although you did not see fit to read and consider it as part of your work in the case, you will agree with me that the IARC's publications on the cancer-causing capability of chemicals are reliable authorities, right?"

That is what happened in Paige. The expert who had not considered the ASTM standard nonetheless testified in deposition that the ASTM standards and methods are well-recognized and that ASTM is generally founded on good science and accepted in the scientific community.

But the witness might fight back: "No counsel, I can't really agree with that. Some IARC reviews are and some aren't; it varies and there is no categorical rule on the point."

Is it over? Not yet -- there are still two more roads to traverse.

The cross-examiner might now turn to the judge: "Your Honor, I now ask the court to take judicial notice of the proposition that this IARC publication is reliable authority."

The ins and outs of the judicial notice approach are beyond the scope of this article -- there are many, they are technical -- but it is enough to say that the court is unlikely to accede to the request, especially if counsel is dropping it all on the court and the other party for the first time in the midst of trial. (For more on judicial notice, see my article in the 2018 ABTL Report, "Hey, Judge, Did You Happen to Notice...?")

There is one more option and it is elegant: Counsel can establish that the IARC review is a reliable authority through a different witness; under this hypothetical, the defense expert. But wait -- there's a timing problem, right? How does the defense establish that the IARC review is reliable via the defense expert -- whose trial testimony is days away -- so the plaintiff's expert can be cross-examined on it today?

This is where advance planning comes in and it centers around compliance with the rules of Code of Civil Procedure Section 2034.010 et seq. and Kennemur.

In response to the demand for disclosure of expert information under Section 2034, the defense must provide a brief narrative statement of the general substance of the expert's expected testimony. Section 2034.260(c)(2). Therefore, the defense should include in the narrative that the expert is expected to testify that the IARC review is reliable authority. Likewise, when the expert is later deposed, the expert must make sure to include the opinion if the question is asked, "Have we now covered the gist of all the opinions you plan to offer at the time of trial?" If not, the expert may be precluded from so opining under Kennemur v. State of California, 133 Cal. App. 3d 907, 917 (1982) (expert may not testify at trial to opinions not disclosed pretrial to an appropriate deposition question). Again, disclose the opinion in writing and be sure the expert testifies to it in deposition.

Now, many weeks later from the deposition and during trial, defense counsel wishes to cross-examine plaintiff's expert on the IARC review which, recall, the plaintiff's expert has not heretofore considered. Defense counsel can do so via an offer of proof. She will advise the judge -- at sidebar in a jury trial -- "Your Honor, in our case in chief, we will present a qualified expert who has already offered the opinion in deposition that the IARC review article is reliable authority, and on that basis and on that representation, I now intend to cross-examine the witness on the stand under Section 721(b)(3)." Counsel's representation is easily verifiable by reference to the deposition transcript. The court likely will permit the examination.

When the shoe is on the other foot and it is the defense expert who has willfully blinded himself from the unhelpful authoritative review article -- the one, say, from the EPA that says chemical X does cause pancreatic cancer in humans -- the situation for plaintiff is simpler. This is because plaintiff can get the "reliable authority" foundation established in her case in chief at trial. It is in effect setting the trap later to be sprung.

During the direct testimony of plaintiff's expert at trial, the following occurs: "Oh, doctor, I did have one more question for you. Are you aware that EPA published a comprehensive review last year concerning the capability of chemical X to cause various kinds of cancer including pancreatic cancer in humans?"

The witness responds, "Oh yes, I am well aware of that review, counsel."

Question: "Doctor, you have already told the court of all your years of experience in studying and evaluating the scientific literature. Based on that experience, do you have an opinion that you can state with a reasonable degree of scientific probability whether the EPA review article is reliable authority?"

Answer: "Oh my, yes. Highly reliable authority in my opinion."

This is the foundation necessary for plaintiff's counsel now to cross-examine the defense expert, several days later, on the plaintiff-favorable EPA conclusion. But again, the technicalities of Section 2034 and Kennemur must be adhered to, this time by plaintiff. Plaintiff should disclose the opinion in writing in compliance with CCP Section 2034.260(c)(3) and provided in plaintiff's expert's deposition. Otherwise, "Objection, Kennemur" will be sustained. (For more on Kennemur, see my article in the 2017 ABTL Report,"Stay Clear of the Kennemur Objection.")

Evidence Code Section 721(b) is a powerful cross-examination tool because it permits counsel to show the factfinder that reliable authorities disagree with an opposing expert's key opinions during that expert's trial testimony. Be sure you know how to use it. 


Submit your own column for publication to Diana Bosetti

Related Tests for Evidence


Last words: On dying declarations

By Ashfaq G. Chowdhury


How to do things with words

By Ashfaq G. Chowdhury


Civil litigation hearsay exceptions

By Elia V. Pirozzi, Alex Ricciardulli


Utilizing the power of requests for admission

By Robert A. Roth


The use of hearsay during restraining order hearings

By Dean Hansell, Bryant Y. Yang


Official records hearsay exception

By Elia V. Pirozzi, Alex Ricciardulli


Experts and hearsay rules: cross versus direct

By Lawrence P. Riff