California Civil Jury Instructions (CACI)
435. Causation for Asbestos-Related Cancer Claims
A substantial factor in causing harm is a factor that a reasonable person would consider to have contributed to the harm. It does not have to be the only cause of the harm.
[Name of plaintiff] may prove that exposure to asbestos from [name of defendant]’s product was a substantial factor causing [his/her/[name of decedent]’s] illness by showing, through expert testimony, that there is a reasonable medical probability that the exposure was a substantial factor contributing to [his/her] risk of developing cancer.
New September 2003; Revised December 2007
Directions for Use
If the issue of medical causation is tried separately, revise this instruction to focus on that issue.
If necessary, CACI No. 431, Causation: Multiple Causes, may also be given. Unless there are other defendants who are not asbestos manufacturers or suppliers, do not give CACI No. 430, Causation: Substantial Factor.
Sources and Authority
- “In the context of a cause of action for asbestos-related latent injuries, the plaintiff must first establish some threshold exposure to the defendant’s defective asbestos-containing products, and must further establish in reasonable medical probability that a particular exposure or series of exposures was a ‘legal cause’ of his injury, i.e., a substantial factor in bringing about the injury. In an asbestos-related cancer case, the plaintiff need not prove that fibers from the defendant’s product were the ones, or among the ones, that actually began the process of malignant cellular growth. Instead, the plaintiff may meet the burden of proving that exposure to defendant’s product was a substantial factor causing the illness by showing that in reasonable medical probability it was a substantial factor contributing to the plaintiff’s or decedent’s risk of developing cancer. The jury should be so instructed. The standard instructions on substantial factor and concurrent causation remain correct in this context and should also be given.” (Rutherford v. Owens-Illinois, Inc. (1997) 16 Cal.4th 953, 982–983 [67 Cal.Rptr.2d 16, 941 P.2d 1203], original italics, internal citation and footnotes omitted.)
- “The term ‘substantial factor’ has not been judicially defined with specificity, and indeed it has been observed that it is ‘neither possible nor desirable to reduce it to any lower terms.’ This court has suggested that a force which plays only an ‘infinitesimal’ or ‘theoretical’ part in bringing about injury, damage, or loss is not a substantial factor. Undue emphasis should not be placed on the term ‘substantial.’ For example, the substantial factor standard, formulated to aid plaintiffs as a broader rule of causality than the ‘but for’ test, has been invoked by defendants whose conduct is clearly a ‘but for’ cause of plaintiff’s injury but is nevertheless urged as an insubstantial contribution to the injury. Misused in this way, the substantial factor test ‘undermines the principles of comparative negligence, under which a party is responsible for his or her share of negligence and the harm caused thereby.’ ” (Rutherford, supra, 16 Cal.4th at p. 969, internal citations omitted.)
- “[A] very minor force that does cause harm is a substantial factor. This rule honors the principle of comparative fault.” (Bockrath v. Aldrich Chem. Co. (1999), 21 Cal.4th 71, 79 [86 Cal.Rptr.2d 846, 980 P.2d 398], internal citation omitted.)
- “Contrary to defendant’s assertion, the California Supreme Court’s decision in Viner v. Sweet (2003) 30 Cal.4th 1232 [135 Cal. Rptr. 2d 629, 70 P.3d 1046] (Viner) did not alter the causation requirement in asbestos-related cases. In Viner, the court noted that subsection (1) of section 432 of the Restatement Second of Torts, which provides that ‘the actor’s negligent conduct is not a substantial factor in bringing about harm to another if the harm would have been sustained even if the actor had not been negligent,’ ‘demonstrates how the “substantial factor” test subsumes the traditional “but for” test of causation.’ Defendant argues that Viner required plaintiffs to show that defendant’s product ‘independently caused [plaintiff’s] injury or that, but for that exposure, [plaintiff] would not have contracted lung cancer.’ Viner, however, is a legal malpractice case. It does not address the explicit holding in Rutherford that ‘plaintiffs may prove causation in asbestos-related cancer cases by demonstrating that the plaintiff’s exposure to defendant’s asbestos-containing product in reasonable medical probability was a substantial factor in contributing to the aggregate dose of asbestos the plaintiff or decedent inhaled or ingested, and hence to the risk of developing asbestos-related cancer, without the need to demonstrate that fibers from the defendant’s particular product were the ones, or among the ones, that actually produced the malignant growth.’ ” Viner is consistent with Rutherford insofar as Rutherford requires proof that an individual asbestos-containing product is a substantial factor contributing to the plaintiff’s risk or probability of developing cancer.” (Jones v. John Crane, Inc. (2005) 132 Cal.App.4th 990, 998, fn. 3 [35 Cal.Rptr.3d 144], internal citations omitted.)
- “ ‘A threshold issue in asbestos litigation is exposure to the defendant’s product. . . . If there has been no exposure, there is no causation.’ Plaintiffs bear the burden of ‘demonstrating that exposure to [defendant’s] asbestos products was, in reasonable medical probability, a substantial factor in causing or contributing to [plaintiff’s] risk of developing cancer.’ ‘Factors relevant to assessing whether such a medical probability exists include frequency of exposure, regularity of exposure and proximity of the asbestos product to [plaintiff].’ Therefore, ‘[plaintiffs] cannot prevail against [defendant] without evidence that [plaintiff] was exposed to asbestos-containing materials manufactured or furnished by [defendant] with enough frequency and regularity as to show a reasonable medical probability that this exposure was a factor in causing the plaintiff’s injuries.’ ” (Whitmire v. Ingersoll-Rand Co. (2010) 184 Cal.App.4th 1078, 1084 [109 Cal.Rptr.3d 371], internal citations omitted.)
- “Plaintiffs may prove causation in an asbestos case by demonstrating that the plaintiff’s or decedent’s exposure to defendant’s asbestos-containing product in reasonable medical probability was a substantial factor in contributing to the aggregate dose of asbestos the plaintiff or decedent inhaled or ingested, and hence to the risk of developing asbestos-related cancer.” (McGonnell v. Kaiser Gypsum Co., Inc. (2002) 98 Cal.App.4th 1098, 1103 [120 Cal.Rptr.2d 23], internal citations omitted.)
- “Many factors are relevant in assessing the medical probability that an exposure contributed to plaintiff’s asbestos disease. Frequency of exposure, regularity of exposure, and proximity of the asbestos product to plaintiff are certainly relevant, although these considerations should not be determinative in every case. Additional factors may also be significant in individual cases, such as the type of asbestos product to which plaintiff was exposed, the type of injury suffered by plaintiff, and other possible sources of plaintiff’s injury. ‘Ultimately, the sufficiency of the evidence of causation will depend on the unique circumstances of each case.’ ” (Lineaweaver v. Plant Insulation Co. (1995) 31 Cal.App.4th 1409, 1416–1417 [37 Cal.Rptr.2d 902], internal citations omitted.)
3 Witkin, California Procedure (4th ed. 1996) Actions, § 527
Flahavan et al., California Practice Guide: Personal Injury (The Rutter Group) ¶¶ 2:767.2, 2:984d, 5:180.2
1 Levy et al., California Torts, Ch. 2, Causation, § 2.03 (Matthew Bender)
California Products Liability Actions, Ch. 2, Liability for Defective Products, § 2.22, Ch. 7, Proof, § 7.06 (Matthew Bender)
33 California Forms of Pleading and Practice, Ch. 380, Negligence, § 380.72 (Matthew Bender)