Two Questionable Expert Evidence Rulings:

In Gass v. Marriott Hotel Services, Inc., 558 F.3d 419 (6th Cir. 2009), the plaintiffs claimed that after exposure to a "cloud" of pesticides in their hotel room, they suffered from "multiple chemical sensitivity" resulting in a variety of symptoms. The district court held that the plaintiffs' experts were not qualified to determine what pesticides the plaintiffs were exposed to, at what levels, or whether their exposure caused their symptoms. The district court therefore granted summary judgment to the defendants. On appeal, the Sixth Circuit agreed that the experts' exposure and causation testimony was inadmissible, but held that under Michigan law the case could nevertheless go to the jury on what amounts to a res ipsa loquitor theory. Judge Danny Boggs, dissenting, persuasively argues that its beyond the common knowledge of lay jurors to determine whether a variety of symptoms that have many different causes can be attributed to an unknown dose of chemicals that have not been positively identified. It's certainly rather strange for a court to hold, as the majority did, that a medical doctor is not qualified to testify regarding causation, but lay jurors can nevertheless draw an inference of causation from common knowledge. My own antenna are raised by the diagnosis of "multiple chemical sensitivity," which has never been shown to exist as a medical condition, except perhaps in the realm of psychosomatic illness.

And speaking of MCS, in Kennedy v. Eden Advanced Pest Technologies, 222 Or.App. 431, 193 P.3d 1030 (Or. App. 2008), the court wrote an atrocious opinion allowing in MCS evidence. Here are a few choice quotes:

Although the American Board of Medical Specialties does not recognize "environmental medicine" [formerly known, and discredited as, "clinical ecology"] as a specialty, the American Academy of Environmental Medicine does. Again, the implication from those facts is that there exists a legitimate debate within the scientific community between two groups of scientists. For example, Rea testified that his technique for determining the existence of chemical sensitivity in a patient is commonly used in the medical community to which he belongs. In contrast, Burton suggested that only "fringe" medical practitioners would diagnose for toxic illness in the manner that Rea does. In our view, the trial court, in performing its gatekeeping function, need not keep from the jury evidence that demonstrates only such a conflict among professionals [editor: like the conflict between mainstream biologists and creationists?].

Moreover, we observe that the evidence is in conflict about the "potential rate of error" of Rea's diagnostic technique. Burton testified that the error rate is 100 percent, a statement that follows ineluctably from his view that chemical sensitivity does not exist. But a jury might not have been persuaded of that premise in light of Rea's qualifications and clinical experience... [shouldn't the court be looking at the scientific evidence for MCS, not the qualifications and experience of the expert? Homeopaths are well "qualified" in homeopathy and can be experienced as well, but that hardly speaks to the reliability of homeopathy. Maybe the court would allow experienced Reiki specialists to testify to the magnetic energy fields their "healing touch" conveys...]

"Indeed, even defendants' expert agreed that chemical sensitivity is not a new or previously unheard of diagnosis, having been first proposed in 1940." [So? Astrology is even older!]

And my personal favorite. After acknowledging that many other jurisdictions have excluded MCS evidence:

Under Oregon law, however, the proper inquiry is not whether MCS or chemical sensitivity is a "valid" diagnosis or is recognized by other jurisdictions; rather, we must, on the record in this case, "decide whether truthfinding is better served by admission or exclusion."

I am very curious to know how allowing a jury to hear expert testimony of invalid diagnosis can "better serve truthfinding" than excluding such testimony.

In the court's defense, it relied on Jennings v. Baxter Healthcare Corp., 331 Or. 285, 14 P.3d 596 (2000), itself one of the worst post-Daubert expert evidence opinions. Oregon adopted Daubert when it thought the opinion provided a liberal admissiblity standard, but declined to adopt a meaningful reliability standard once it became clear that the full Daubert trilogy, codified in amended federal Rule 702, was far from a let-it-all-in standard. The end result is allowing all sorts of quackery into Oregon courts.

I'm opening up comments for a few hours.