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Risky Cause: Rutherford and its Progeny

by Raphael Metzger, Esq.


Three years ago the California Supreme Court issued a landmark toxic tort decision in Rutherford v. Owens-Illinois, Inc. (1997) 16 Cal.4th 953.  Rutherford was a lung cancer case brought by a life-long smoker who claimed that his cancer was caused by asbestos to which he was exposed from working on ships.  The case went to trial only against Owens-Illinois. The jury found for Rutherford, apportioning 1.2% of fault to Owens-Illinois, 2.5% to Rutherford, and 96.3% to asbestos companies with whom Rutherford had settled before trial.

The Rutherford court held that to prevail on an occupational cancer claim, the plaintiff need not prove that exposure to the defendant’s product actually caused his cancer, but need only show that the exposure was a substantial factor in increasing his risk of developing cancer.  Id. at 982.

In adopting the substantial factor standard, the Court found that a plaintiff “cannot be expected to prove the scientifically unknown details of carcinogenesis, or trace the unknowable path of a given asbestos fiber”.  Id. at 976.  Instead, “we can bridge the gap in the humanly knowable” by requiring a plaintiff to show that his exposure to a defendant’s product was a substantial factor in contributing to his aggregate exposure, and thus a substantial factor in increasing his risk of developing cancer. Id. A plaintiff need not demonstrate that exposure to the “fibers of the defendant’s particular product were the ones, or among the ones, that actually produced the malignant growth.”  Id. at 977.  

The Court explained that “the substantial factor standard is a relatively broad one, requiring only that the contribution of the individual cause be more than negligible or theoretical.”  Id., 16 Cal.4th at 978.  The Court noted that the standard had been formulated “to aid plaintiffs as a broader rule of causality than the ‘but for’ test.”  Id. at 969.  The Court explained that it is only where the defendant’s product plays merely a “theoretical” or “infinitesimal” part in bringing about an injury that it is not a substantial factor.  Id.

Defendants in toxic tort cases have since argued that Rutherford is limited to multi-defendant asbestos cancer cases and has no other application.  The Rutherford court did not indicate whether its liberal causation rule would apply in other situations, so there has been some uncertainty about the scope of the new rule.  However, two subsequent cases have clarified that the liberal rule does apply to carcinogens other than asbestos and that it applies in cases where only a single product is alleged to cause cancer.

The first case to apply Rutherford was Bockrath v. Aldrich Chemical Company (1999) 21 Cal.4th 71, in which a plaintiff who had multiple myeloma sued many chemical companies claiming that exposure to their products caused his cancer.  Although the case did not involve asbestos, the Supreme Court found the Rutherford rule applicable, stating: “In Rutherford . . . we addressed the question of proof of causation in ‘the context of products liability actions.’”  Bockrath at 79 (citing Rutherford at 968).  The Court determined that the Rutherford rule applied to Mr. Bockrath’s case because the case involved “complicated and possibly esoteric medical causation issues.”  Id.

Using the causation rule applied in Rutherford as the basis of its holding, the Court listed the elements that must be plead in a toxic exposure action.  The Court held that a plaintiff must: (1)
allege that he was exposed to each of the toxic materials claimed to have a specific illness; (2) identify each product that allegedly caused the injury; (3) allege that as a result of the exposure, the toxins entered his body; (4) allege that he suffers from a specific illness, and that each toxin that entered his body was a substantial factor in bringing about, prolonging, or aggravating that illness; and (5) allege that each toxin absorbed was manufactured or supplied by a named defendant.  See id. at 80.

Recently, in Kennedy v. Southern California Edison Co., (July 20, 2000) 2000 Daily Journal D.A.R. 8013, the Ninth Circuit applied Rutherford to a radiation-leukemia case in which the defendants contended that the plaintiff’s chronic myelogenous leukemia (CML) was caused by something other than radiation at the nuclear power plant where the plaintiff worked.  The Kennedy court began its analysis by noting that the California Supreme Court had applied Rutherford to claims involving exposure to substances other than asbestos in Bockrath. The court then addressed the more difficult issue of whether Rutherford applies in single product cases.

The Kennedy court found “little relevant distinction between a Rutherford case with multiple defendants, each of whose products may have been a substantial factor in causing the plaintiff's injury, and a case in which a single defendant argues that the plaintiff cannot show causation because there exist other potential sources that may have been the legal cause of the harm.”

The Court explained that “[i]n both circumstances, the plaintiff is faced with the same hurdles that the California Supreme Court identified as making proof of causation, absent the Rutherford instruction, nearly impossible, [since], on a scientific level, the uncertainty regarding the biological mechanisms by which asbestos leads to lung cancer parallel the medical uncertainties surrounding the cause and effect relationship between CML and radiation.”  The Court also reasoned that “it is just as impossible to prove the course of radiation as it is to prove the ‘unknowable path of a given asbestos fiber.’" Id. 2000 Daily Journal D.A.R. at 8015.

However, the Kennedy court found the defendant’s alternative cause defense an even more compelling reason to apply the Rutherford standard: “More importantly, by choosing to raise alternative sources of the injury as a defense, a defendant creates the need for a Rutherford instruction.  Just as the presence of multiple defendants in an asbestos-related cancer case raises the question of ‘whether the risk of cancer created by . . . exposure to a particular asbestos-containing product was significant enough to be considered a legal cause of the disease,’ so too does the proffering of alternative causes of CML by a single defendant.  In both scenarios a given defendant is making essentially the same argument: the plaintiff cannot prove that his injury came from a specific source (i.e. the defendant), when multiple other potential sources exist, whether they be another asbestos-related defendant or something altogether different, such as cigarette smoking or radiation from the sun in the case of CML.”

The Supreme Court in Rutherford and Bockrath, and the Ninth Circuit in Kennedy, have shown appropriate concern for the insurmountable burden a plaintiff has in proving that toxins caused his cancer under the traditional causation standard.  These courts have therefore appropriately modified the traditional standard to allow a plaintiff to establish his case by proving that his exposure to a carcinogenic substance was a substantial factor in increasing his risk of developing cancer.

It is now clear that the Rutherford rule applies to carcinogens other than asbestos and is not limited to multi-defendant or multiple product cases.   Whether the rule applies to diseases other than cancer will be determined in future cases. 
At least plaintiffs, who claim their cancers were caused by occupational exposure to carcinogens and file suit in California, will be assured of having a fair chance of obtaining compensation for their serious injuries.


Raphael Metzger is the principal of the Metzger Law Group, a Professional Law Corporation.  His firm concentrates its practice on occupational cancer, lung disease, and toxic organ failure cases.  The firm’s offices are located in Long Beach, California.

This article was published in the Los Angeles Daily Journal on September 1, 2000 under the title "Risky Cause: Rutherford Rule Applies to Carcinogens Other Than Asbestos."

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