Many of my posts have talked about the need for studies on the health, safety, and environmental effects of nanomaterials. But it has been a long time since I raised the question of what these studies may mean for toxic tort litigation. As in any litigation, the evidence, including scientific studies and the experts who interpret them, must be admissible under the relevant rules of evidence. In the United States, there are two basic approaches to the admissibility of expert evidence in the courts – (1) the federal courts’ approach, which is governed by the Federal Rules of Evidence and a trio of cases beginning with Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993), and (2) the approach known as the Frye test. Regardless of the approach used by the particular court considering the evidence, early studies that may demonstrate health or environmental risks associated with nanomaterials will have an uphill battle for admissibility in the courts.
Over the next month, I intend to discuss some of these issues in a series of posts. This post will consider the first question: What is it about this evidence that will be so difficult for the courts?
To begin with, let’s briefly look at the rules for admissibility of the evidence in court:
1. Frye Test: This test derives from the case of Frye v. United States, 293 F. 1013 (D.C. Cir. 1923), a criminal case that involved a scientific lie-detection technique that was a sort of precursor to the modern lie-detector tests. The court there said that “while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.” Thus, courts view as admissible under this test only expert evidence derived from scientific studies or techniques in general use, and usually long-standing use, in the particular field, and which most experts in the field recognize as being reliable.
2. Daubert Test: The Daubert case itself was a toxic tort, a prescription drug product liability action, so the Supreme Court had before it on the record scientific studies that resemble the kinds of studies of exposure-and-outcome that might be produced for nanomaterials. The Supreme Court held that the test for admissibility of expert evidence under the Federal Rules is broader than the Frye test and requires that the proponent of the evidence demonstrate that it be reliable – i.e. that it be scientifically valid – and that it be relevant to a particular issue in the case, not that it merely be suggestive of health problems. The Court emphasized that the trial judge is the “gatekeeper” who must make a determination at an early time in the litigation as to whether the expert evidence is admissible. If it is not admissible, often plaintiffs’ cases are dismissed prior to trial.
What evidentiary challenges will nanomaterial studies present?
● The studies will provide only probabilistic evidence. This means that the studies will only show statistical associations (probabilities) between exposure to a particular nanosubstance and a particular outcome (e.g. illness). While the extent to which probabilistic evidence differs from traditional forms of proof in tort cases (such as motor vehicle accidents) is a matter of degree, the inability of the studies to confirm the causal relationship between exposure to a substance and the illness the plaintiff suffers will be problematic for plaintiffs’ cases.
● The illnesses are likely to be “generic.” Some substances previously studied are linked to “signature diseases,” which occur very rarely in the general population, but with greater frequency among people exposed to the substance. Silicosis (silica dust), asbestosis (asbestos), and pleural mesothelioma (asbestos) are examples. But most cancers, respiratory conditions, and neurological disorders, for example, are caused by a variety of triggers, some related to exposures, others genetic or idiopathic. It is therefore difficult to differentiate those caused by a particular exposure and those arising for other reasons.
● The nanostudies will be new. Under either admissibility test, new and untested or unreplicated studies may not pass muster. In toxic torts, history has shown that early plaintiffs may have considerable difficulty with the admissibility of their evidence; even if the evidence is ruled admissible, problems of proof arise because juries may not view the early evidence as having much weight. As time goes on, these studies may gain more acceptance in the field – or, they may be proved to be aberrations.
Next up: Admissibility and scientific reliability of nanostudies.