The Expert Impeachment Witness: Fight the Facts, Not the Opinion

Apr 29, 2018

"Like a house built on sand, the expert's opinion is no better than the facts upon which it is based." This famous line from Kennemur v. State of California, 133 Cal. App. 3d 907, 924 (1982), can be found in virtually every California motion to exclude an opponent's expert witness. And it is typically cited for one of two arguments:

There is the junk science argument. This argument seeks to show the expert's reasoning or methodology is unreliable. It is used against the expert who opines the plaintiff suffers from clinical depression, and bases that opinion on plaintiff's palm readings and Ouija board score. 

Next is the you-have-your-facts-wrong argument. This is for the expert who opines that the car involved in the accident had a defective brake system. The car the expert examined may have a defective break system, but it is a different car than what was actually involved in the collision. 

So long as testifying experts have been properly designated pursuant to California's Code of Civil Procedure section 2034.260 et seq., they are generally free to offer either argument (or both) to debunk their opponent's expert at trial. But what about experts who were not formally designated? Are there any grounds (or reasons) to call an expert who was not designated? 

Section 2034.310 provides as follows:

A party may call a witness at trial an expert not previously designated by that party if ... [¶] (b) That expert is called as a witness to impeach the testimony of an expert witness offered by any other party at trial. This impeachment may include testimony to the falsity or nonexistence of any fact used as the foundation for any opinion by any other party's expert witness, but may not include testimony that contradicts the opinion

(Italics added). 

Section 2034.310 essentially draws a line between (1) calling an expert who will argue the opposing expert presented junk science or reached the wrong conclusion (not allowed), and (2) calling an expert who will argue the opposing expert got his or her foundational facts wrong (allowed). Accordingly, when parties dispute the permissibility of impeachment expert testimony, the issue turns on whether the witness will present opinion or fact evidence. 

Kennemur acknowledged the difficulty drawing this line because, "[i]n a philosophical sense, all factual testimony by a witness, lay or expert, is opinion, i.e., the witness' belief as to what actually occurred. [¶] Nevertheless, when it comes to impeaching expert witnesses, the distinction between an opinion and a foundational fact—though arbitrary—must be made." 133 Cal. App. 3d at 924. 

Tire Tracks Crossing Into Oncoming Traffic? 

To best understand how courts decide the admissibility of impeachment expert testimony, let us start with an examination of Kennemur—Section 2034.310 essentially codifies the rule that Kennemur created

The case began when Plaintiffs Diane and Robert Kennemur sued the state of California for failing to adequately warn of ice on a highway. Id. at 911. Ms. Kennemur was driving southbound on a state highway in her 1974 Volkswagen Beetle. A 1975 Mustang was headed northbound, and as it rounded a curve, Ms. Kennemur's VW crossed over the center-line directly into its path. The VW hit the Mustang at an angle. Ms. Kennemur suffered severe permanent injuries including brain stem damage, which left her a quadriplegic. She was still in a coma at the time of trial, three and one-half years after the collision. Id. 

The State called an accident reconstruction expert as part of its defense. Id. at 912. The expert's ultimate opinion was that "the accident was caused 'because the driver [Ms. Kennemur] put for some reason an excessive amount of left steer into the vehicle, crossed into the oncoming lane, and the vehicle coming along its own lane hit it. It's just that simple.'" Id. The expert based his opinion on (1) testimony from an eye witness, and (2) accident scene photographs. The Court explained that the expert's ultimate opinion "was based entirely upon another opinion—that the tracks crossing the center-line in the photographs belonged to the VW." Id. at 922.   

After concluding the expert's testimony, the State rested. Plaintiffs' attorney sought to call several expert witnesses "in rebuttal." Id. Plaintiffs first wanted to call an accident reconstruction expert. However, when deposed by the State's counsel, the expert testified he was only focused on the Volkswagen, a defendant at that time. "[A]s far as the roadway was concerned, he was going to leave that portion of the accident reconstruction to another expert...." Id. at 913.

That admission notwithstanding, Plaintiffs' attorney sought to have their expert testify "in rebuttal" and offer "... the opposite opinion[:] that the tracks in the photographs did not belong to the VW and his reasons for such an opinion." Id.  at 922. The trial court indicated that it would not permit the Plaintiffs' expert to substantively contradict the opinions of the State's expert, and Plaintiffs' appealed.  

Plaintiffs first argued they were permitted to have their expert testify about tire tracks because the State should have known the expert would opine on tire tracks. Plaintiffs argued: "Since [the State] knew that [Plaintiffs' expert] was an accident reconstruction expert, the [S]tate should have anticipated that [Plaintiffs' expert] would form an opinion contrary to [State's expert] concerning the tracks in the photographs." Id. at 919. The Court disagreed, the Court explained that, "[w]hen appropriate demand is made for exchange of expert witness lists, the party is required to disclose not only the name, address and qualifications of the witness but the general substance of the testimony the witness is expected to give at trial.... [T]his means the party must disclose either in his witness exchange list or at his expert's deposition, if the expert is asked, the substance of the facts and the opinions which the expert will testify to at trial." Id.

Plaintiffs next argued they should be permitted to call their expert witness to impeach the State's witness. Put another way, the State's witness testified that the tire marks in the photograph belonged to the VW. Plaintiffs—the argument went—should be able to impeach that testimony by having their expert contradict that foundational fact (i.e., not an opinion), and testify that the tire marks did not belong to the VW. Plaintiffs argued that any evidence offered in rebuttal, which would "substantively" contradict the State's expert witness, was proper impeachment. Id. at 921.  

To reach its decision, the Court asked the following: "[W]hat is meant by 'impeachment' as the term is used [in expert witness discovery]?" Id. The Court considered the general definition of impeachment from Black's Law Dictionary, but explained that "[i]n the law of evidence, however, the word 'impeachment' has a more restricted meaning." The Court turned to Evidence Code section 780, and held that impeachment was limited to "any matter going to the truthfulness of the testimony of the witness to be impeached." Id. at 922 (emphasis added). 

Applying this rule to the facts, the Court explained that "[u]nder the rules of impeachment, a foundational fact underlying an expert's opinion is treated differently than the opinion itself." Id. at 923. While impeaching experts may be called to show that foundational facts are false or nonexistent, impeaching experts may not be called to contradict or challenge opinions. The Court then explained the interpretation of impeachment should be narrow: "If a liberal rule of interpretation were adopted to permit impeachment by contradiction of an expert's opinion, the legislative intent manifested in the expert witness disclosure statutes (i.e., reasonable notice to the opposing party of the expert's expected testimony) would be thwarted because everything constituting the basis of the ultimate opinion could be classified as a fact." Id.

Turning to Plaintiffs' intended impeachment experts, the Court held that "the photographs depicting the tire tracks and [the eye witness'] testimony were the foundational facts upon which [the State's expert] based his opinion that the tracks belonged to the VW." Id. at 924 - 25 (italics added). Accordingly, Plaintiff's expert could not "impeach" the testimony with another expert reaching a different opinion (i.e., that the tire tracks did not belong to the VW). Instead, the scope of permitted impeachment would be more limited: "If [Plaintiffs] sought to prove by expert testimony that the photographs were false, i.e., that they did not accurately depict the accident scene or that [the eye witness'] testimony was inherently improbable, this would have been proper impeachment ... under Evidence Code section 780, subdivision (i)." Id. at 925.   

Alcohol-Breath = .08? 

A similar result is found in Mizel v. City of Santa Monica, 93 Cal. App. 4th 1059 (2001). Mizel was a slip and fall case where the plaintiff, Gerald Mizel, fell on an access ramp at Shutters on the Beach, a well-known Santa Monica hotel. Mr. Mizel's injuries were severe. He was taken by ambulance to the hospital where he was examined by an orthopedic surgeon on call. Id. at 1065. Mr. Mizel suffered serious damage to his shoulder; the ball portion of his left shoulder was replaced with a titanium prosthetic, and the mobility of his shoulder was permanently disabled. Id.

Mr. Mizel presented testimony at trial by the orthopedic surgeon, Dr. O'Brien who examined him at the hospital. Dr. O'Brien testified that he (and other medical personnel) made the following note in Mr. Mizel's records: "strong smell of ETOH" (i.e., strong smell of alcohol). Id. at 1066. 

On cross-examination, Defendants' counsel asked Dr. O'Brien a series of questions relating to how much a person would have to drink in order to smell of alcohol. Id. The questions were framed in a way to "elicit responses based upon Dr. O'Brien's medical school training." Id. (italics in original). However, Dr. O'Brien refused to concede that someone who smelled of alcohol must have consumed a significant amount. Dr. O'Brien testified as follows:

Once you develop a smell for alcohol, ... you have a very keen smell, and you can smell it very easily.... Well, the alcohol was potentially a significant—at that point we're just gathering data and possibly contemplating emergency surgery, and so we gather every bit of data that we can. And at that point in time it was simply an observation that there was a smell of alcohol.


Dr. O'Brien was asked whether he was aware of published studies concluding that alcohol cannot be reliably detected until the person is approaching a blood-alcohol level of .08. Dr. O'Brien refused to concede the point:

I am aware of my own experience, and after you spend as many hours in the emergency room as I have, throughout my training, and after you have treated as [many] people as I have, who have consumed various levels of alcohol, you realize that the study may not always be correct, whatever study you are referring to. And I have a very keen sense of smell, especially for alcohol.... [I]n life-saving measures or [when we are] contemplating anesthesia, we don't know if we're going to have to immediately take him to surgery at that point. And so the presence of alcohol would be important for the anesthesiologist to note....

Id. at 1067. 

Without Dr. O'Brien conceding that Mr. Mizel was impaired at the time of his accident, Defendants sought to call another expert, Dr. Stewart Moskowitz, who had conducted studies relating to the consumption of alcohol. Dr. Moskowitz had not been designated as an expert, but Defendants indicated they intended to call him to impeach Dr. O'Brien. Id. Defendants argued that Dr. Moskowitz would "demonstrate the falsity of a matter upon which Dr. O'Brien had based his opinion." Id. The trial court refused to allow Dr. Moskowitz to testify because "it was 'in effect ... an expression of opinion, and ... does not qualify under the exception of [Code of Civil Procedure section 2034.310]." Id. 

The Court of Appeal affirmed. The Court reasoned that while Section 2034 may allow testimony about facts underlying the expert's opinion, "Dr. Moskowitz was expected to render a contrary opinion, not, as defendants suggest, to contradict the underlying factual foundation of Dr. O'Brien's testimony." The Court explained:

... Dr. Moskowitz was to testify, based upon his training, research, and studies, including his experience with professionals in the field, that alcohol can only be detected through smell when there has been consumption to a blood-alcohol level in the range of .08. This testimony would not challenge the foundational facts of Dr. O'Brien's testimony, which were based upon his personal education and experience.

Id. at 1068.

The scope of impeachment is limited. It is high-stakes poker to keep an expert witness secret with the hopes he or she will be able to catch the opposing expert flatfooted by attacking his or her factual foundation at trial. The discovery statutes are designed to encourage the exchange of information, and courts are reluctant to endorse what it could perceive as an unfair surprise. Litigators are best served to play it safe: When in doubt, designate and exchange.    

David Sugden is a shareholder at Call & Jensen. He can be reached at [email protected].

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