But For Causation in Defective Drug and Toxic Exposure Cases: California s Form Jury Instruction CACI 430

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1 But For Causation in Defective Drug and Toxic Exposure Cases: California s Form Jury Instruction CACI 430 By Matt Powers and Charles Lifland Since the California Supreme Court s 1991 decision in Mitchell v. Gonzales, 1 California has endorsed the use of the substantial factor test described in the Restatement (Second) of Torts to determine causation in torts cases. 2 As set out in the Judicial Council of California s Civil Jury Instruction No. 430 ( CACI 430 ), the substantial factor test seems both simple and easy for jurors to understand: conduct is a factual cause of an injury if that conduct is a factor that a reasonable person would consider to have contributed to the harm. 3 CACI 430 also includes the following optional bracketed language: Conduct is not a substantial factor in causing harm if the same harm would have occurred without that conduct. See CACI Defendants in most products liability cases, however, should not treat the bracketed language as merely optional -- an instruction without that language can put defendants at a serious disadvantage, and counsel representing product manufacturers should argue for its inclusion whenever possible. The problem is fundamental. When the bracketed language is omitted, a jury may believe that they can find conduct to be a cause of an injury even if the evidence shows that the plaintiff would have suffered the injury in the absence of the defendant s wrongful conduct. Indeed, that is one of the criticisms that the current draft of the new Restatement (Third) of Torts levels against the substantial factor test -- it may lure the factfinder into thinking that a substantial factor means something less than a but-for cause Restatement (Third) of Torts: Liability for Physical Harm 26 Comment j (Proposed Final Draft No. 1, issued April 6, 2005) Cal. 3d 1041 (1991). 2 Mitchell v. Gonzales, 54 Cal. 3d 1041 (1991); see also Restatement (Second) of Torts, (1965). 3 CACI CACI 430 reads, in full: A substantial factor in causing harm is a factor that a reasonable person would consider to have contributed to the harm. It must be more than a remote or trivial factor. It does not have to be the only cause of the harm. [Conduct is not a substantial factor in causing harm if the same harm would have occurred without that conduct.] 5 See also id. ( To the extent that substantial factor is employed instead of the but-for test, it is undesirably vague. As such, it may lure the factfinder into thinking that a substantial factor means something less than a but-for cause or, conversely, may suggest that the factfinder may distinguish among factual causes, determining that some are and some are not substantial 1

2 The risk of confusion is even greater in cases where the plaintiff claims to have suffered an otherwise common injury after exposure to a toxic substance or prescription drug. In those cases, using CACI 430 without the bracketed language implies that simply increasing the risk of an injury is enough to show that a defendant s product is a cause of (i.e., a factor actually contributing to) their injury. That confusion is even more likely if the court also includes CACI 431 in the charge -- CACI 431 reiterates that negligence may combine with another factor to cause harm and that a defendant cannot avoid liability just because some other person, condition, or event was also a substantial factor in causing [the harm]. Part of the problem lies with the language of the test itself. After all, what does it mean for a product to be a factor in an injury? In a recent case applying Washington law, In re Hanford Nuclear Reservation Litigation, 2007 WL (9 th Cir. 2007), the Ninth Circuit considered claims by plaintiffs who developed cancer and other diseases after exposure to a radioactive chemical emitted from a plutonium-production facility. In their suit against the facility s operators, the plaintiffs offered evidence that the chemical could increase the risk of diseases like theirs. In rebuttal, the defendant introduced evidence that the plaintiffs had risk factors for their diseases (e.g., genetics, smoking) that were unrelated to their exposure. Under CACI 430, the jury would have been instructed to find that the defendants chemical was a cause of the plaintiffs injuries if the chemical contributed to the harm. But unless the court also told the jury that [c]onduct is not a substantial factor in causing harm if the same harm would have occurred without that conduct, a juror might reasonably conclude that the chemical was a factor in a plaintiff s disease -- and therefore a cause of the harm -- even if that same juror found that the plaintiff would have developed the same cancer without any exposure to the defendants chemical. The substantial factor test was never intended to eliminate the requirement that a defendant s conduct be a but for cause of (i.e., a necessary condition for) the plaintiff s injury. See, e.g., Viner v. Sweet, 30 Cal. 4 th 1232, 1239 (2003); Restatement (Second) of Torts, 432(1). 6 Instead, it was intended in part to deal with cases involving multiple causes independently capable of causing the plaintiff s injury. 7 In such cases, the tortfeasors factors. Thus, use of substantial factor may unfairly permit proof of causation on less than a showing that the tortious conduct was a but-for cause of harm or may unfairly require proof greater than the existence of but-for causation. ). 6 See also Restatement (Second) of Torts, 432(1) (1965) ( Except as stated in subsection (2), 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 ); Viner v. Sweet, 30 Cal. 4th at 1239 ( The [plaintiffs] respond that in Mitchell v. Gonzales, this court repudiated the but for test of causation in tort cases alleging negligence. Not so.... Mitchell recognized that the substantial factor test subsumes the but for test. (citation omitted, emphasis added)). 7 See also id. at 432(2) ( [If] two forces are actively operating... and each of itself is sufficient to bring about harm to another, the actor s negligence may be found to be a substantial factor in bringing it about. ); Restatement (Third) of Torts: Liability for Physical Harm 26 & Comment j (Proposed Final Draft No. 1, issued April 6, 2005) ( with the sole exception of 2

3 responsible for the multiple independent causes could avoid liability -- and leave the injured plaintiff with no remedy -- by pointing out, in turn, that the conduct of their fellow tortfeasors would have caused the injury even in the absence of their own negligent conduct. That original purpose of the pure substantial factor test probably explains its widespread adoption by California courts in asbestos cases. Many of those cases appear to support the notion that showing a product increased the risk of an injury is enough to show that a product is a cause of that injury. 8 But those cases illustrate a special circumstance rather than a general rule of toxic tort causation. Because asbestos cases typically involve signature injuries that are rare without asbestos exposure, asbestos plaintiffs generally have little difficulty showing that exposure is a but for cause of their injury -- asbestosis, for example, does not occur in the absence of asbestos exposure. Instead, the dispute in such cases centers on identifying which particular defendants manufactured the asbestos products that injured the plaintiff and whether a particular defendant should be liable given its contribution to the overall exposure. In this context, a pure substantial factor test arguably makes sense -- at least under some circumstances 9 -- where there is no question that the plaintiff s exposure to asbestos caused the injury. But it is one thing to refuse to absolve a negligent defendant of liability because the negligence of other defendants was independently sufficient to cause the plaintiff s asbestosrelated disease. It is quite another to relieve plaintiffs of having to prove that their overall exposure to a product was a but for cause of their injury. Defense counsel should also be wary of attempts to cast other possible causes of an injury as multiple, independent causes. Again, the recent Ninth Circuit case applying Washington law nicely illustrates this point. Plaintiffs claimed they developed a variety of illnesses after exposure to radiation from the Hanford Nuclear Weapons Reservation. They urged the court to expand the substantial factor doctrine and apply the test when there are potentially multiple causes of each plaintiff s injury, such as smoking, genetics, or pregnancy, even though Plaintiffs cannot show that Hanford radiation alone would have been sufficient to cause the injury. multiple sufficient causes, substantial factor provides nothing of use in determining whether factual cause exists. ) 8 See, e.g., Rutherford v. Owens-Illinois, Inc., 16 Cal. 4 th 953, 998 (1997) ( In an asbestos-related cancer case [t]he plaintiff may meet the burden of proving that the 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. ); Jones v. John Crane, 132 Cal. App. 4 th 990, 1000 (2005) ( Rutherford does not require that each exposure be sufficient to independently cause lung cancer. To the contrary, the exposure need only be a substantial factor in contributing to the aggregate dose of asbestos the plaintiff inhaled ) (quoting Rutherford, 16 Cal. 4 th at 976). 9 The details of medical causation in exposure cases can be complicated, and occasionally other causation analyses are appropriate. For example, the specifics of the plaintiff s injury might mean that one particular defendant s product was the only but for cause of an injury, but that it is impossible to determine which defendant was responsible. Or, it might be that the injury is divisible, e.g., one defendant s conduct aggravated an injury caused by another. The problems presented by such situations are beyond the scope of this article. 3

4 Hanford, 2007 WL at *17. Citing Comment j to section 26 of the draft Restatement (Third) of Torts, the Court rejected plaintiffs attempt to cast those other possible causes as multiple, independent causes that could justify using the substantial factor test: [Plaintiffs ] reading of Washington law would allow the substantial factor test to supplant but-for causation in virtually all toxic tort cases. Id. In most drug and toxic exposure cases, California law provides plenty of ammunition to argue in favor of the bracketed CACI 430 language. California courts have repeatedly held that the substantial factor test does not eliminate the concept of but for causation. See, e.g., Viner, 30 Cal. 4 th at 1240; Mitchell, 54 Cal. 3d at Instead, the substantial factor test adopted by the Supreme Court in Mitchell subsumes and includes the but for test of causation. See Viner, 30 Cal. 4th at 1239 ( The [plaintiffs] respond that in Mitchell v. Gonzales, this court repudiated the but for test of causation in tort cases alleging negligence. Not so.... Mitchell recognized that the substantial factor test subsumes the but for test. (citation omitted, emphasis added)). See also Mayes v. Bryan, 139 Cal. App. 4th 1075, (2006) (holding that the but for concept is included in the substantial factor test, but finding that a failure to instruct on but for caused no prejudice in that case). And, in drafting CACI 430, the Judicial Council recognized the continued viability of the but for concept. Specifically, the Judicial Council recognized that, in cases where CACI 430 is used, plaintiff must prove that but for defendant s conduct, the same harm would not have occurred. See CACI 430 (Directions for Use). The Council stated that the bracketed language, which clarifies this concept for the jury, could be used to clarify the substantial factor test except in cases where plaintiff claims a concurrent independent cause i.e., multiple causes that are each capable, by themselves, of causing the injury. Id. Plaintiffs suffering from signature injuries caused by multiple defendant tortfeasors (e.g., asbestos claims) might qualify as claiming concurrent independent causes -- but many drug and toxic tort cases involve concurrent dependent causes like those described in Hanford. Developing evidence that a plaintiff s injury could have occurred in the absence of any exposure is, of course, a key part of these arguments. In one recent case, for example, the Court of Appeal held that omitting the bracketed language in CACI 430 was not error -- even as the court acknowledged that the substantial factor test includes the but for causation concept. See Mayes, 139 Cal. App. 4 th at But because there was no evidentiary support for defendants contention that [the plaintiff] would have died even had [the defendant] not acted negligently, the court held that it was not reasonably probable defendants would have received a more favorable result even had the court instructed on but for causation. Id. at 1096, 97. The current draft of the Restatement (Third) of Torts: Liability for Physical Harm abandons the substantial factor language entirely on the grounds that it is simply confusing and, with few exceptions, provides nothing of use in determining whether factual cause exists. 10 Concurrent independent causes are multiple forces operating at the same time and independently, each of which would have been sufficient by itself to bring about the harm. Viner, 30 Cal. 4th at 1240 n.3. In contrast, a concurrent dependent cause occurs when two forces act simultaneously to produce an injury, but neither force by itself would be sufficient to cause the injury. See id. at

5 See id. at 26, Comment j. 11 Perhaps California will eventually adopt the new Restatement (Third) as it did the Restatement (Second). But for now, counsel representing product manufacturers in California toxic tort and prescription drug cases should at minimum make and preserve arguments that the jury charge should include the additional bracketed language of CACI 430 making clear that the defendant s product must, indeed, be a but-for cause of the plaintiff s injury. 11 See id. (noting that the treatment of substantial factor in both [previous] Torts Restatements is confusing. ) See also id. ( with the sole exception of multiple sufficient causes, substantial factor provides nothing of use in determining whether factual cause exists. ). 5