California Court of Appeal Allows Non-Medical Experts to Opine on Specific Causation in Asbestos


A California Court of Appeal panel recently broadened a plaintiff’s ability to prove specific causation by holding that a plaintiff need not retain a medical professional to opine that the defendant’s product was a substantial factor in causing the plaintiff’s injuries.  Hernandez v. Amcord, Inc., 2013 WL 1682468 (Cal.Ct.App., Apr. 18, 2013).


In Hernandez, the plaintiff, the wife of a deceased carpenter and construction worker, sought to prove that an asbestos-containing cement product used by her husband and manufactured by the sole defendant remaining at trial was a substantial cause of her husband’s mesothelioma.  The only specific testimony at trial regarding the product indicated that the decedent used the product “a lot of times” and removed the product from bags by cutting the bag down the middle, thereby creating dust around his face, and then dumping the product from the bag into a mixer.


The plaintiff also presented two expert witnesses to opine on causation.  The first, an epidemiologist, did not review any case-specific documentation, yet testified that if a worker poured a 94-pound bag of plastic cement containing asbestos that worker would be at an increased risk for developing mesothelioma as long as the asbestos fibers were respirable and airborne.  The epidemiologist stated that his opinion was to a “reasonable scientific certainty.”  The second expert witness, a pulmonary pathologist, reviewed the case-specific records and opined that he believed, to a reasonable degree of medical probability, that the decedent’s mesothelioma was caused by asbestos.  The plaintiff did not present any expert to testify that he or she believed, to a reasonable degree of medical probability, that the defendant’s product was a substantial factor in causing this decedent’s mesothelioma.


After the plaintiff’s case, the defendant moved for nonsuit on the issue of causation, arguing that the plaintiff failed to show that the defendant’s product caused the decedent’s mesothelioma, as required by Rutherford v. Owens-Illinois, Inc., 16 Cal.4th 953 (1997).  The trial court agreed, finding that someone “with an M.D. after his name” must testify, to a reasonable degree of medical probability, that the product was a substantial factor in causing the decedent’s injury.


The California Court of Appeal disagreed and clarified that a plaintiff must satisfy two elements to prove causation.  First, the plaintiff must establish some threshold exposure to the product at issue.  Second, the plaintiff must establish that, in reasonable medical probability,  the exposure to the product at issue was a legal cause of the plaintiff’s injury.  Critically, the court interpreted Rutherford to mean that the second element can be met by simply showing that, within reasonable medical probability, the product at issue was a substantial factor in contributing to the plaintiff’s risk of developing cancer.  Therefore, since the epidemiologist testified that there would be an increased risk  of developing cancer if one worked with the defendant’s product in the manner in which the decedent did, that testimony, combined with the pulmonologist’s opinion that the mesothelioma was caused by exposure to asbestos, satisfied the court’s threshold for specific causation.

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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