Poster 6

ELEMENTS OF A CIVIL LAWSUIT

Second Element of Liability:

Causation

PROXIMATE CAUSE

Tort law breaks causation into two questions:

   Cause in Fact: Was the defendant’s conduct or activity a substantial factor leading to the plaintiff’s injury? Would the plaintiff’s injury have happened anyway?

The plaintiff must introduce evidence which affords a reasonable basis for the conclusion that it is more likely than not that the conduct of the defendant was a cause in fact of the result.@ Keaton et al., Prosser & Keaton on the Law of Torts '41, at 269-70 (5th ed. 1984).

   Proximate Cause: Is the plaintiff’s injury such a remote, improbable, or unforeseeable consequence of the defendant’s action that the defendant should not in fairness be responsible for it?

For the purposes of using risk information, the issue is almost always causation in fact C whether there was a physical causal connection between the activity/product and the injury C rather than remoteness or unexpectedness.

GENERAL OR SPECIFIC CAUSATION

In re Agent Orange, 611 F. Supp. 1223 (E.D.N.Y. 1985).
Judge Weinstein distinguished between Astrong and Aweak versions of the preponderance test as it applies to causation. Under the strong version . . . statistical correlation alone indicating that the probability of causation exceeds fifty percent are insufficient; some particularistic or anecdotal evidence, that is proof that can provide direct and actual knowledge of the causal relationship between the defendant’s tortuous conduct and the plaintiff’s injury. . . The weak version of the preponderance rule converts the statistical probability into a legally absolute finding that the causal connection did or did not exist in the [plaintiff’s individual] case. 597 F. Supp. 740, 735-36 (E.D.N.Y. 1984).

General causation = The defendant’s toxin must (more probably than not) be capable of causing the type of illness that the plaintiff has.

In re TMI Litigation Consolidated Proceedings, 927 F. Supp. 834 (M.D. Pa. 1996).
The court rejected the plaintiffs’ claims of injury due to exposure to radiation from the Three Mile Island accident in 1979 on the ground that they could not demonstrate that radiation at the dose levels that plaintiffs could reasonably demonstrate had adverse effects. The fact that radiation at higher levels was known to cause the adverse effects that the plaintiffs complained of was insufficient to sustain their burden of proof. 

In re Hanford Nuclear Reservation Litigation (E.D. Wash. August 21, 1998) (unreported; opinion) available at http://www.hanford.gov/docs/ruling.html.
Approximately 3,000 plaintiffs in this consolidated litigation alleged current or future injury (including thyroid, gastrointestinal (GI) and other cancers and thyroid diseases) as a result of exposure to radioactive (I-131 and Pu-239) and non-radioactive emissions from the Hanford Nuclear Reservation in Washington State. In this 762-page order granting partial summary judgment to the defendants (the federal government and its contractors), the court resolved the generic causation phase of the litigation. The court applied a strict Adoubling of risk@ threshold as the legal standard for evaluating the sufficiency of plaintiff’s evidence related to radiation exposure and for determining which claims should be heard by a jury. In response to plaintiffs claims of GI cancer from exposure to hexavalent chromium (AGrVI@) in drinking water from the Columbia River, the court considered whether it is scientifically proper for plaintiffs expert to extrapolate from animal data to opine that CrVI is capable of causing GI cancer in humans. In the face of overwhelming epidemiologic data, it appears that dismissal of animal data would probably be justified by the court. Where there is no relevant epidemiological evidence (as in this case), however, the court left open the possibility that scientifically reliable animal data might be adequate to support a finding that a given chemical is capable of causing human disease. In the current case, the specific animal data for Cr VI was found not to be reliable. Finally, referring to Daubert and the court’s role of gatekeeper, the court observed, AThe complexity of the evidence in this case, indeed the mere appearance of complexity and the manipulation of numbers in some instances, could easily inspire the most astute jury to reach an erroneous conclusion that exposure to Hanford emissions was a cause in fact of an individuals disease.@ The court also excluded, under this standard, the dose reconstruction reports of several of the plaintiffs’ experts. [Reith (Applegate)]

Specific causation = This particular plaintiff’s illness was caused by exposure to the defendant’s toxin.  This requires proof of three elements:

Actual Exposure ...

... By This Defendant’s Product ...

... Caused This Plaintiff’s Illness

Poster  7a

ELEMENTS OF A CIVIL LAW SUIT

Second Element of Liability:

Causation (Cont.)

Evidence Issue No. 1: Admissibility of Risk Evidence

LEGAL STANDARDS

Relevant: must Tend to Make an Element of Proof More or less Probable

Fed. R. Evid. 401, Definition of Relevant Evidence.
Relevant evidence means evidence having any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.

In re Agent Orange, 611 F. Supp. 1223, 1241 (E.D.N.Y. 1985).
The court excluded animal data from consideration regarding causation because animals were exposed to much higher concentrations of dioxin and because animals are different biological species than humans.

Reliable

Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S.579 (1993).
In Daubert the plaintiff’s expert sought to rely on a meta-study that combined separate epidemiological studies concerning the teratogenicity of Bendectin. On appeal, the Supreme Court clarified what the new standard for admissibility of scientific evidence was under Federal Rules of Evidence. The Court held that reliable scientific knowledge is assessed according to whether the reasoning or methodology underlying the testimony is scientifically valid. More specifically, the reliability of scientific evidence could be determined through several factors, none of which is necessarily required in any particular instance. The factors are:

  falsifiability (whether the theory or technique can be tested);

  peer review and publication;

 the known or potential rate of error and the existence and maintenance of standards controlling the technique’s operation; and

  general acceptance of the methodology within the scientific community. [Poulter]

Not Prejudicial in Relation to Its Probative Value

Fed. R. Evid. 403, Exclusion of Relevant Evidence on Grounds of Prejudice, Confusion, or Waste of Time.
Although relevant, evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.

APPROACHES

Let it in - The Jury Decides

Ferebee v. Chevron Chemical Co., 736 F.2d 1529 (D.C. Cir. 1984).
This case characterized the question whether the plaintiff’s condition was caused by the herbicide Paraquat to be a classic Abattle of the experts,@ in which the plaintiff was permitted to present experts who would testify to causation, despite a limited background in toxicology.

Ambrosini v. Labarraque, 966 F.2d 1464 (D.C. Cir. 1992).
Would chemical in vitro cellular studies and in vivo animal studies be insufficient, in all cases, to support a conclusion that a particular drug caused birth defects? Several federal appellate courts in recent years have asserted that animal studies, in certain circumstances, may be admissible in toxic tort litigation. In 1992, the D.C. Circuit Court of Appeals in Ambrosini v. Labarraque emphasized that Richardson v. Richardson-Merrell, Inc., infra, did not hold that in vitro and in vivo studies always would be insufficient to support a finding that a particular drug is a human teratogen. The defendants in Ambrosini sought to rely on Richardson. The Ambrosini decision by Appeals Court Chief Judge Mikva appears not to preclude the use of animal and cellular studies as a partial basis for an inference of causation in a toxic injury case where those study findings reinforce the human (epidemiological) data. A plaintiff’s expert had offered epidemiological evidence that a class of drugs including the suspect drug, in general, do cause birth defects. But the lower court found this unexamined evidence to be inadmissible after reviewing an affidavit of a defendants’ expert that relied on several negative epidemiological studies. In reversing the district court’s grant of summary judgment in favor of the drug manufacturer and plaintiff’s physician, and in distinguishing between Ambrosini and Richardson, the Court of Appeals declared:

When a court denies the right to have a jury decide a disputed issue, especially one of a scientific nature, its reasons for doing so must be strong. Science is a rapidly changing field. Methodologies rejected today may be universally accepted in the future. Our decisions must leave the way open for these changes. 

The use of animal evidence is well established in setting public health policy and developing regulatory standards from probabilistic data on population risk, but there is presently no such acceptance in determining the scientific basis for personal risk and individual causation. This case contributes to the future possibility that health risk assessments relying partially or even heavily on animal and cellular data will be found admissible in toxic injury lawsuits. [Roth-Nelson]

Hottinger v.Trugreen Corp. 665 N.E. 2d 593 (Ind. Ct. App. 1996).

Will fallout from Bradley v. Brown, 42 F.3d 434 (7th Cir. 1994), which found the scientific foundation of Multiple Chemical Sensitivity (MCS) disorder to be unreliable, lead to excluding other, more reliable evidence of a toxic chemical injury? In 1996 the Indiana Court of Appeals reversed a district court finding of summary judgment in favor of defendant’s argument that Bradley applied to a case of herbicide exposure. Indiana Evidence Rule 702 requires that expert scientific testimony, to be admissible, must rest on reliable scientific principles. In Steward v. State, N.E. 2d490 (Ind. 1995), the Indiana Supreme Court held that Daubert is useful in applying the Indiana Rule. In ruling that the trial court had abused its discretion in granting summary judgment, the appeals court contrasted the generally unreliable MCS evidence in Bradley with the substantially reliable evidence of nervous system injury in Hottinger:

  A specific statistical association between exposure to the herbicide 2,4-D and nervous system injury, and, therefore, the inference of general causation, was established in peer-reviewed journals as early as1959, including in the Journal of the American Medical Association.

 A brain scan was used to show diminished blood flow and scalloping in lobes of the brain consistent with other brain scan findings in patients exposed to neurotoxic chemicals. A peer-reviewed journal had accepted for publication a paper by an expert in this case that explained this methodology.     

 

Poster  8a

ELEMENTS OF A CIVIL LAWSUIT

Second Element of Liability:

Causation (Cont.)

Evidence Issue No. 2: Sufficiency and Weight of Risk Evidence

Does the risk evidence have sufficient "weight" to meet the applicable standard of proof?

JURY QUESTION

NOT ADMISSIBLE  /  CONCLUSIVE

GENERAL CAUSATION

  "Epidemiological threshold" for mass tort cases: Conclusive epidemiological evidence is often required to show proof of human harm

  Epidemiological evidence is preferred but not required

Merrell Dow Pharmaceuticals, Inc. v. Havner, 907 S.W.2d 535 (Tex.App. 1994).
Does recovery of damages in a toxic tort lawsuit require evidence of statistically significant human (epidemiological) studies that demonstrate a positive association between a toxic agent and a toxic injury? In 1994 the Texas Court of Appeals decided Merrell Dow Pharmaceuticals, Inc. v. Havner. The appellate court had previously reversed a jury verdict because plaintiffs' experts could not cite one epidemiological study that found a statistically significant association between a suspect teratogen and the plaintiff's birth defects. On original submission a panel of this court found no evidence to support causation, but in a rehearing en banc (full court), the jury verdict was affirmed with respect to both admissibility and sufficiency of evidence for causation (Chief Justice dissenting). A changed interpretation of the epidemiological evidence followed these findings: 

Biological causation is inherently difficult to assess based on epidemiological studies. That thalidomide causes limb reduction defects based solely on epidemiological studies cannot be proved although the scientific community accepts that it does. Only one drug (Accurate) has been proven teratogenic over the past 25 years though epidemiological studies alone. None of the numerous negative epidemiological studies has the requisite size and statistical power to detect a change in the rate of limb reduction defects occurring by themselves and not as part of a cluster of birth abnormalities, nor do most of them specify when during the pregnancy the drug exposure occurred.

A reanalysis of the relative risk (RR) or association between the suspect drug and the plaintiff's birth defects that accounts for the mother's exposure during the first trimester rather than merely during the pregnancy as a whole, or at the time ingestation when fetal limb formation is critical, results in RR = 2.13, a positive association, instead of 0.97, which is inconclusive. Reanalysis of epidemiological data and the resulting opinion of a scientist is not, as a matter of principle, insufficient to support a finding of causation in any case. Such reanalysis is a methodology that the FDA and EPA use to verify reports They get from the industries they regulate.

Epidemiology is considered a "soft" science because the researcher cannot experimentally control the variables, as compared to the "hard" science of laboratory animal testing. The EPA relies solely on animal studies to determine the effects of most chemicals, while the FDA relies heavily on animal studies in the early stages of drug approval.

The potential influence of this case on risk analysis may be to place the limitations of epidemiology in perspective so that many flawed human studies are no longer consistently preferred as evidence of causation over carefully designed and controlled animal studies. [Roth‑Nelson]

See also Green, supra, at 672‑74, observing that courts in both Agent Orange and Bendectin cases generally adopted "an epidemiological threshold, or more restrictively, a statistically significant epidemiological threshold for plaintiffs to establish in order to create a submissive case," but noting that not all Bendectin courts did so.

For non-mass tort cases, the courts may be particularly willing to excuse the absence of epidemiological evidence.

Ferebee, supra; see generally Gerald W. Boston, A Mass‑Exposure Model of Toxic Causation: The Content of Scientific Proof and the Regulatory Experience, 18 Colum. J. Envtl. L. 181, 274‑351 (1993), discussing differences in adjudication of mass toxic tort cases and those involving isolated injuries.

EPIDEMIOLOGY CASES

Lackie v. Smith Kline Beecham F.Supp (D.D.C.1997).
How strict is the standard of scientific proof for causation just so a claim for toxic chemical injury may reach a jury and not be declared inadmissible? The U.S.District Court for the District of Columbia denied the defendant's motion for summary judgment sought on grounds that plaintiff's expert testimony was inadmissible under Daubert. At issue was how rigorous is Daubert's standard of proof, not for a jury to find causation with sufficient certainty, but just to take a claim before a jury.

Absence of positive epidemiological studies specific to the plaintiff's theory of causation. The court found it is not fatal to the admissibility of expert testimony under Daubert especially where the disease is a rare disorder, as long as the methodology employed is sound. The court cited recent review of Benedi v. McNeil P.P.C. 66 F.3d 1378 (4th Cir. 1995). In Lackie myelodysplastic syndrome (MDA), a bone marrow disorder clearly linked with exposure to benzene, was accompanied by deletion of the long arm of the fifth chromosome (5q-minus). The 5q-minus variant of MDA occurs at a rate between 1 in 100,000 and 1 in a million. Such a rare variant itself cannot be the subject of epidemiological study, as such a study would have to cover the whole U.S. population. But all MDA disorders collectively have been studied carefully and clearly linked to benzene exposure. The court found the plaintiff's theory of causation in to be a far cry from the theories advanced by plaintiffs in the Bendectin cases, where an overwhelming body of epidemiological evidence had contradicted the experts' conclusions. Raynor v. Merrell Pharmaceuticals, Inc.,104 F.3d 1371 (D.C. Cir. 1997).

Absence of a differential diagnosis that eliminated all causes other than benzene exposure. The court deemed it was not particularly significant that doctors could not eliminate a spontaneous mutation of a chromosome as an alternative cause, nor must the expert eliminate each and every possible alternative cause. This was found especially true where a plaintiff could establish a definitive link between the causative agent (benzene) and the general condition it produced(MDS). In citing Mendes Silva v. United States, 980 F.2d1482, 1487 (D.C. Cir. 1993), the court observed: The fact that several possible causes might remain "uneliminated" only goes to the accuracy of the conclusion, not the soundness of the methodology.

Absence of an exact level of exposure and dose. Defendants argued that the benzene content in contaminated denture adhesive varied from lot to lot and plaintiff's experts relied on testing samples other than those actually used 10 years earlier, so there was no reliable evidence of the benzene amount actually absorbed. But the court declared the plaintiff should not be held to such an exacting standard of proof, and drew a comparison with cases such as Christopherson v. Allied SignalCorp., 1106 (5th Cir. 1991), where there was credible information regarding dosage. [Roth Nelson]