| The Hon. Richard Ulmer of the San Francisco Superior Court recently issued an order holding that "every exposure" opinions are inconsistent with the causation standard set forth in Rutherford v. Owens Illinois, Inc. (1997) 16 Cal. 4th 953. Judge Ulmer noted that "but for" proximate causation - that a defendant's conduct is a cause of plaintiff's injury only if the injury would not have occurred "but for" defendant's conduct - is not the law in California asbestos cases after Rutherford. However, the court went on to state that expert "opinions based on a notion that any and all exposures to asbestos are necessarily substantial factors in contributing to the risk of developing asbestos-related cancer" are contrary to Rutherford. The court recognized that Rutherford involves a two-step process to prove causation in asbestos related cancer cases. First, it must be proven that a plaintiff was exposed to a particular defendant or third party's asbestos-containing product. Second, it must be proven to a "reasonable medical probability" that the particular party's product "was a substantial factor in contributing to the aggregate doses of asbestos the plaintiff inhaled or ingested, and hence, to the risk of developing asbestos-related cancer." Judge Ulmer noted that "[w]ere it true that any and all asbestos exposures are invariably substantial factors, there would be no need for Rutherford's second step, for any exposure would qualify." (emphasis in original). Judge Ulmer further identified two important questions addressed by the supreme court in Rutherford that "closely bracketed its core holding": - "whether the risk of cancer created by a plaintiff's exposure to a particular asbestos-containing product was significant enough to be considered a legal cause", (page 975) and
- "which exposures to asbestos-containing products contributed significantly enough to the total occupational dose to be considered 'substantial factors' in causing the disease." (page 977).
Judge Ulmer recognized that those questions would not have been asked if "each and every exposure to an asbestos-containing product - regardless of number or size - is automatically a substantial factor." Judge Ulmer concluded his ruling by stating that "it is appropriate under Rutherford to ask whether an exposure to asbestos was sufficient, or significant enough, to be considered a legal cause of the risk of disease. Conversely, it is not appropriate to opine that every asbestos exposure is necessarily a legal cause." Judge Ulmer's ruling is significant because it recognizes that "every exposure" opinions are inappropriate under California's Rutherford standard. This decision provides further persuasive authority supporting defense efforts to limit or exclude the testimony of plaintiffs' experts who fail to support their causation opinions with scientific and medical evidence demonstrating that a particular exposure was a substantial factor. This article is presented for informational purposes only and is not intended to constitute legal advice. | 
