In response to HP’s Motion For Summary Judgment in a case where there was evidence of asbestos exposure from the client’s products, the Untied States District Court for the Central District of California crystallized the causation requirement: “In an asbestos tort action in federal court, is a plaintiff required to proffer expert causation testimony that is specific to the dose of asbestos attributable to a particular defendant to survive a motion for summary judgment? Based on a comprehensive review of the case law, the Court concludes that the answer to that question is yes, at least absent an extraordinary showing of actual exposure by a particular defendant’s product.” The Court then granted summary judgment: “It simply cannot be the case that proffering any evidence of amount, frequency, and duration is sufficient to allow a jury to decide if that exposure is substantial, because, like the ‘every exposure’ theory, it would allow even fleeting exposures to be enough, so long as the plaintiff offered specific evidence… the Court agrees with the balance of courts that, particularly in cases with multiple defendants, ‘causation requires that an expert connect the nature of the asbestos exposure and pair it with a Daubert-approved methodology that can be used to determine whether such an exposure was a substantial cause of the (plantiff’s) injury.’ ” Carpenter, et. al., v 3M Company, Case No. CV 20-11797-MWF, December 6, 2022.

The Court started its analysis with McIndoe v Huntington Ingalls Inc., 817 F.3d 1170, which was argued to the 9th Circuit by Edward Hugo in 2016 and “which all parties acknowledge is the leading binding case on this issue”. “In McIndoe, the Ninth Circuit made clear that even if there is evidence of exposure, asbestos plaintiffs must produce evidence that any such exposure was a substantial contributing factor to the relevant injuries. Carpenter takes McIndoe one step further “requiring an expert to testify that the relative dose from a particular defendant was significant enough to allow a jury to find in favor of its being a substantial factor.”