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Impeachment or Contradictory Opinion?

Attorneys are required to designate experts prior to the time of trial.  Generally, unless an expert was designated and revealed to the other side ahead of time, they are not permitted to testify at the time of trial.  This is to remove gamesmanship and surprise at the time of trial.  For the sake of fairness, an expert must be disclosed such that the other side may be afforded the opportunity to review their findings and take their deposition ahead of trial and learn what opinions they intend to offer at the time of trial.

An exception to this rule is codified in Code of Civil Procedure § 2034.310.

“A party may call as 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 the 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.”

Thus, an undesignated expert can be called for “impeachment” purposes.  A recent case delved into what this actually means.  That case is Pina v. County of Los Angeles, (2019) 38 Cal. App. 5th 531.

Vincent Pina brought a personal injury suit against the County of Los Angeles and Los Angeles County Sheriff’s Department (collectively the County), alleging, among other things, that the County negligently caused a bus on which he was a passenger to strike a pillar in 2013.

Mr. Pina denied injury immediately after the accident but reported pain soon thereafter, obtaining treatment and diagnoses of spinal injury from, among others, Gary Chen, M.D.  At trial, Pina admitted sustaining injury in a separate bus accident in 2016, for which he sued the Los Angeles County Metropolitan Transportation Authority (MTA). The County also introduced evidence that Vincent Pina was struck by a car in 2010.

Dr. Chen opined that the 2013 accident caused the injuries for which Mr. Pina claimed damages, including injuries requiring future surgery.

Pursuant to Code of Civil Procedure § 2034.310(b), [the impeachment exception discussed above], the trial court allowed the County to call Robert Wilson, M.D.—an undesignated expert —for the purpose of impeaching Dr. Chen. Dr. Wilson testified that Dr. Chen was wrong about the cause of appellant’s injuries and the need for surgery.

The jury found for the County and Mr. Pina appealed, arguing the testimony offered by the County’s “impeachment” expert, Dr. Wilson, was improper and should not have been permitted.

The Court of Appeal agreed with Mr. Pina and made two holdings:

  1. A county’s undesignated medical expert was subject to exclusion because the county had ample opportunity to augment its expert witness list after learning that Pina’s treating physician had recommended surgery, but the county neither made such a motion nor offered the expert for deposition;
  2. Impeachment of the treating physician’s testimony under Code Civ. Proc., § 2034.310, was permissible to the extent that the undesignated expert addressed the foundational fact of a medical test result, but the trial court exceeded its discretion and prejudicially erred by allowing the expert to testify to the effect that the treating physician lacked supporting evidence and misunderstood or misapplied medical science, which did not concern foundational facts and likely affected the jury’s verdict on medical damages.


Specifically, the Court of Appeal took issue with the type of impeachment offered by Dr. Wilson.  The Court stated:

Although the term “impeach” is susceptible to an interpretation encompassing the offering of contrary opinion, permissible impeachment by an undesignated expert is narrower in scope.  Indeed, the Legislature has codified the distinction between permissible impeachment and contrary opinion: “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.” “[R]ather than broadly construing what a foundational ‘fact’ is, the term should be strictly construed by the trial court to prevent a party from offering a contrary opinion of his expert under the guise of impeachment.”
Pina v. County of Los Angeles (2019) 38 Cal.App.5th 531, 546

Dr. Wilson contradicted Dr. Chen’s causation opinion (that the 2013 accident caused appellant significant injury) by opining that it was not medically substantiated by the X-rays, the MRI results, and the presentation of appellant’s injuries. Dr. Wilson supported this contrary causation opinion with two additional opinions, testifying (1) that “medical knowledge and medical literature” supported neither Dr. Chen’s finding (in support of his causation opinion) of a significant change between the 2013 and 2016 X-rays, nor his interpretation of that change as reflecting a traumatic event; and (2) that the force applied to appellant’s body in the 2013 accident was insufficient to cause appellant’s injuries.

The Court held that these contrary opinions did not concern the falsity or nonexistence of foundational facts on which Dr. Chen relied. Dr. Chen expressly disclaimed any opinion on the degree of force involved in the 2013 accident, admitting he did not know how hard the bus struck the pillar.

As a result, the Court found that Dr. Wilson’s opinion regarding the degree of force had no relation to the factual foundations of Dr. Chen’s opinions.  The Court said that, in delivering his other causation opinions, Dr. Wilson similarly failed to challenge the veracity of the facts on which Dr. Chen relied.  Instead, he testified to the effect that Dr. Chen misunderstood or misapplied medical science; Dr. Wilson then advanced a contrary understanding of that science based, among other things, on research studies purportedly establishing that 99 percent of disc protrusions are caused by degenerative change and unspecified sources establishing that a bone fracture or major ligament disruption is necessary to find a significant change between X-rays. This testimony exceeded the scope of permissible impeachment.

Dr. Wilson also contradicted Dr. Chen’s opinion that appellant would require future surgery, opining, in response to a request from the County’s counsel to identify “a difference of opinion” with Dr. Chen, that appellant “had no indications of needing surgery.” Dr. Wilson supported this contrary opinion with matters unrelated to the factual foundations of Dr. Chen’s opinion, including his independent examination of appellant (referenced only generally, without mention of any factual findings contrary to those on which Dr. Chen relied) and a purported conclusion of the American Academy of Orthopedic Surgeons that surgery is generally unwarranted for back pain associated with degenerative disc disease.

Finally, the Court contrasted this impermissible impeachment testimony with Dr. Wilson’s testimony that the MRI results did not show nerve compression – which the Court held permissibly impeached Dr. Chen’s testimony regarding what the MRI showed—a foundational fact relevant to Dr. Chen’s medical opinions.

The Court of Appeal reversed the jury’s finding and remanded the case back to the Superior Court for a new trial.

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