Tort causation

When damage causation is probabilistic, as in the case of the effects of synthetic substances on human health, torts inappropriately manage risk because it is difficult to link individual exposures with individual health outcomes. 

Overinterpretation of laboratory and epidemiologic studies of cancer causation can make cancer-prevention regulations inefficient and ineffective. Similarly, it can lead to unjust resolution of cancer-related toxic torts. In this book VanDoren explains how these difficulties arise and gives valuable insight into how they can be reduced or eliminated by market-driven choices of individuals and companies. ... 

Parson Woodforde concluded that a cat s tail was of the greatest efficacy for such a malady. While the good parson s reasoning was logical, his premise was incorrect. Testimonials often involve the fallacy of post hoc, ergo propter hoc, that is, the assumption that because two events occur sequentially, the first is the cause of the second. (In tort law, causation must be proved.) The swelling of the eyelid may have abated of its own accord even in the absence of the tail of a black cat. Moreover, there is selection bias in testimonials a lack of consequence rarely results in a testimonial and dead men tell no tales. 

Toxic tort litigation has several distinguishing characteristics, including issues of exposure, latency, prospective damages, causation, risk, and complex challenges involving expert testimony and multiplicity of parties. 

In toxic or environmental tort litigation, the plaintiff must prove that the defendant s product was a cause or a substantial factor contributing to her harm. In many cases, however, the evidence of direct causation is difficult to acquire. 

The standards for admissibility of expert testimony to prove causation clearly will continue to impact the future of toxic tort litigation. Therefore, an understanding of the Daubert decision and the continuing debate over the admissibility of expert scientific or medical testimony will benefit anyone dealing with toxic or environmental tort issues. 

Regarding causation analysis, courts often accept testimony from nonphysicians, especially in toxic tort, workers compensation, and product liability cases. 

Among the elements of a case which the plaintiff has the burden of proving is causation-in-fact. This element is common to toxic tort, hazardous waste, occupational disease, and conventional traumatic injury claims. As noted above, causation-in-fact probability is not an issue in most conventional injury cases. The jury simply decides which version of the facts it believes in an all-or-none, yes-or-no fashion, with no room for intermediate probabilities. Causation evidence is not expressed probabilistically. 

The propriety of this kind of mental leaping is one of the most controversial aspects of toxic tort and occupational disease cases, where causation often cannot be properly formulated as a yes-or-no fact. Instead, parties rely on evidence of increased risk or enhanced probability of disease which may or may not be attributable to defendant s conduct. The inquiry becomes one of the existence and magnitude of a fact probability. Therefore, understanding the dual nature of probability, as both a factual statistical quantity (fact probability) and a measure of strength of belief (belief probability), becomes important. Unfortunately, fact probability and belief probability have not been kept analytically distinct. Courts have collapsed the requirements for burden of production and burden of persuasion into one test that blurs plaintiff s twofold task of defining not only the facts or elements to be proved but also the amount of credence to be accorded a fact in support of a finding. When a judge tells a jury that plaintiff must show that causation is more likely than not, she/he risks confusion. Does she/he mean that the fact of causation which plaintiff must prove (burden of production) is not traditional true-or-false (100% vs. 0%)... 

Courts that apply the rule only to fact probabilities essentially seek a yes-or-no belief in a >50% fact probability. By contrast, traditional courts that apply the rule only to belief probabilities seek a >50% belief in a yes-or-no fact. In toxic tort/occupational disease claims where both fact probability and belief probability are issues, there are at least two other approaches. Courts could apply the more-likely than-not standard jointly, reducing alleged fact probability by a factor reflecting the jury s doubt about its truth. By contrast, the rule could be applied sequentially to require only a > 50% belief in a fact probability which itself may barely exceed the >50% threshold. It is important to see that joint application stiffens the causation burden-of-produc-tion/burden-of-persuasion, while sequential application substantially lessens the causation production/ persuasion requirements. The point here is that, regardless of approach, a court that deals with causal indeterminacy characteristic of toxic tort/occupational disease claims should be explicit about what it is doing, especially if defendant s culpability of conduct or duty to prevent risk is factored into determination of the causation issue. 

As noted in previous editions of this chapter, the law of toxic torts continues to develop. Traditional legal rules continue to be strained and stretched. The tension created by the juxtaposition of scientific uncertainty and unsettled law continues to impact toxic tort litigants. The emerging interface of genetic and environmental forces creates new challenges for the proof of causation and injury, and further complicates emerging concepts of latency between exposure and either onset or manifestation of injury. 

Gold S (1986) Note, causation in toxic torts Burdens of proof, standards of persuasion, and statistical evidence. Yale Law Journal 96 376. 

Judicial decisions in nonregulatory contexts such as toxic tort and product liability suits are likewise inconsistent in their consideration of the linear, no threshold model. As in the regulatory context, most cases find no problem with an expert s reliance on a risk assessment using the linear model. In a handful of cases, however, the court rejects reliance on a linear dose-response assumption. Eor example, one court in addressing the cancer risks from a low concentration of benzene in Perrier held that there is no scientific evidence that the linear no-safe threshold analysis is an acceptable scientific technique used by experts in determining causation in an individual instance (Sutera 1997). Another court decision concluded that [t]he linear non-threshold model cannot be falsified, nor can it be validated. To the extent that it has been subjected to peer review and publication, it has been rejected by the overwhelming majority of the scientific community. It has no known or potential rate of error. It is merely an hypothesis (Whiting 1995). The inconsistency and unpredictability of judicial review of risk assessments adds an additional element of uncertainty into the risk assessment process. 

Ricci, P. E., and Gray, N. (1998). Towards a new way to deal with toxic torts Risks in toxic tort law. Part 1 Probabilistic causation and legal causation. Univ New South Wales Law J 21, 787—806. 

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