Business Law

Kline v. Zimmer, Inc. (May 26, 2022, B302544) __ Cal.App.5th ___ [2022 WL 1679539]

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Party not bearing the burden of proof need not present medical causation evidence to a reasonable degree of medical probability.

Gary Kline was implanted with an artificial hip joint manufactured by Zimmer, Inc. The surgery was unsuccessful. Kline underwent further procedures and therapy for the next eight years. He then sued Zimmer on a products defect theory. At trial, the court excluded Zimmer‚Äôs proffered expert testimony regarding possible explanations of Kline‚Äôs persistent pain that were expressed to less than a reasonable medical probability.  In contrast, the court allowed Kline‚Äôs expert to testify that, to a reasonable degree of medical probability, Zimmer‚Äôs defective product caused Kline‚Äôs symptoms. The jury returned a verdict for Kline, and the trial court denied Zimmer‚Äôs motion for posttrial relief.  Zimmer appealed the ensuing judgment. 

The Court of Appeal reversed the judgment and remanded for retrial on whether Zimmer‚Äôs defective product caused Kline‚Äôs alleged harm. The court held that Zimmer was entitled to introduce expert testimony regarding possible (albeit not probable) explanations for Kline‚Äôs symptoms to show that Kline had failed to satisfy his burden of proving that Zimmer caused Kline‚Äôs injuries. The court explained that ‚ÄúZimmer did not need to show that a different cause was more likely than not the cause of Kline‚Äôs injuries. All that Zimmer needed to show was that Kline‚Äôs evidence was insufficient to prove Kline‚Äôs injuries were more likely than not caused by Zimmer. It should have been permitted to do so by offering expert opinions offered to less than a reasonable medical probability that Kline‚Äôs injuries may have been attributable to other causes‚ÄĚ because such testimony ‚Äúcould cast doubt on the accuracy and reliability of a plaintiff‚Äôs expert.‚ÄĚ When the jury is called upon to decide complex issues of medical causation it is ‚Äúimperative that the party without the burden of proof be allowed to suggest alternative causes, or the uncertainty of causation, to less than a reasonable medical probability. To withhold such information from the jury is to deprive it of relevant information in assessing whether the plaintiff has met its ultimate burden of persuasion.‚ÄĚ The court found the error was necessarily prejudicial because it affected a core issue on which expert testimony was needed.

The bulletin describing this appellate decision was originally prepared for the California Society for Healthcare Attorneys (CSHA) by H. Thomas Watson and Peder K. Batalden, who are partners at the appellate firm Horvitz & Levy LLP, and is republished with permission.

For more information regarding this bulletin, please contact H. Thomas Watson, Horvitz & Levy LLP, at 818-995-0800 or

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