Every once in a great while, we read an opinion that stands out as an example of judicial craftsmanship. The facts and issues are explained in clear, lively prose. The reasoning is careful and thorough, leading inevitably to undeniable conclusions. The opinion articulates in a fresh way ideas we have often discussed, bringing to mind Alexander Pope’s definition of wit: “What oft was thought, but ne’er so well expressed.” The author treats the participants in the case with respect and has a sense of humility. Tamraz v. Lincoln Electric Co., Nos. 08-415/4016 (6th Cir. Sept. 8, 2010), available here, is such an opinion.

Jeff Tamraz worked as a welder for 25 years. After he began to suffer symptoms of parkinsonism, he and his wife sued several manufacturers of welding supplies, alleging that the fumes from their products caused his parkinsonism.

The main issue at trial was whether he had Parkinson’s Disease – the most common type of parkinsonism, which usually has an unknown cause – or manganism, a form of parkinsonism with symptoms distinct from Parkinson’s Disease, which is caused by overexposure to – guess what – manganese. Tamraz’s first treating doctor and the defense experts testified that he had Parkinson’s Disease; a hired litigation expert testified that he had manganism. Dr. Walter Carlini, one of Tamraz’s treating neurologists, took a middle ground by testifying that Tamraz did not have manganism, but something akin to Parkinson’s Disease that Dr. Carlini opined was caused by exposure to welding products containing manganese. The jury returned a whopping $20.5 million verdict for plaintiffs. Defendants appealed, contending, among other things, that the trial judge abused her discretion by admitting the opinion of Dr. Carlini about the cause of his disease.

The court started by clarifying that the precise issue was not Dr. Carlini’s diagnosis that Tamraz suffers from a form of parkinsonism, which was undisputed, but his etiology, i.e., his opinion about what caused the disorder. Although Dr. Carlini opined with a reasonable degree of medical certainty that Tamraz has manganese-induced Parkinson, the court showed by carefully parsing his reasoning that his etiology “was at most a working hypothesis, not admissible scientific ‘knowledge.’” Slip op. at 6. Dr. Carlini’s causation opinion was based on Tamraz’s development of Parkinson’s Disease after exposure to welding fumes that presumably contain manganese; the fact that manganese causes manganism and therefore might trigger Parkinson’s Disease as well; literature hypothesizing that toxins combined with genetic factors may cause Parkinson’s Disease; and other less compelling factors. Id. at 6-7.

The court concluded that Dr. Carlini’s opinion that manganese could cause Parkinson’s Disease

is a plausible hypothesis. It may even be right. But it is no more than a hypothesis, and it thus is not “knowledge,” nor is it “based upon sufficient facts or data” or the “product of reliable principles and methods . . . applied . . . reliably to the facts of the case.” Fed. R. Evid. 702.

Slip op. at 7. The court then quoted numerous excerpts from Dr. Carlini’s testimony in which he conceded that many steps in his analysis were based on speculation and that no studies found a link between manganese and Parkinson’s Disease. Id. at 7-8.

In addition to finding that Dr. Carlini had nothing more than a hypothesis that manganese could cause Parkinson’s Disease (in other words, no basis for a general causation opinion), the court explained that Dr. Carlini had no basis for concluding that manganese actually did cause Tamraz’s Parkinson’s Disease (no specific causation, either). Other than exposure to welding fumes, Dr. Carlini could point to no tests or any other objective evidence establishing the causal link in Tamraz. Id. at 8-9. The mere fact that Tamraz has Parkinson’s Disease without a known cause was insufficient because most cases Parkinson’s Disease have unknown causes. Id. And for that reason, the court rejected an attempt to rely on differential diagnosis, which doesn’t work if most cases of a disease have unknown causes. Id. at 13-15.

Tamraz argued that Dr. Carlini’s extensive experience with diagnosing parkinsonism made his causation opinion reliable. The court responded:

But most treating physicians have more training in and experience with diagnosis than etiology. When physicians think about etiology in a clinical setting, moreover, they may think about it in a different way from the way judges and juries think about it in a courtroom. Getting the diagnosis right matters greatly to a treating physician, as a bungled diagnosis can lead to unnecessary procedures at best and death at worst. But with etiology, the same physician may often follow a precautionary principle: If a particular factor might cause a disease, and the factor is readily avoidable, why not advise the patient to avoid it? Such advice – telling a welder, say, to use a respirator – can do little harm, and might do a lot of good. This low threshold for making a decision serves well in the clinic but not in the courtroom, where decision requires not just an educated hunch but at least a preponderance of the evidence.

Slip op. at 11-12 (citation to a bunch of interesting articles omitted).

After finding that the admission of Dr. Carlini’s testimony was not harmless and ordering a new trial, the court concluded with an appropriate nod of respect for Dr. Carlini and a nice explanation of the difference between hypotheses commonly considered by scientists and scientific evidence that can be considered by courts:

No one should construe this opinion as criticism of Dr. Carlini, whom the deposition shows to be intelligent and knowledgeable about the subject matter – immeasurably more so than we are. But not everything a knowledgeable person says is “knowledge” under Rule 702, no more than everything a scientist says is “scientific.” A district judge asked to admit scientific evidence must determine whether the evidence is genuinely scientific, as distinct from being speculation offered by a genuine scientist. This causation opinion fell into the latter category and therefore should have been excluded. The sort of hypothesis Dr. Carlini presented can play a valuable role both in medicine, where, if the costs of action are low, doctors may want to act on hypotheses without further support, and in science generally, where all discoveries started as untested hypotheses. From this perspective, criticizing Dr. Carlini’s hypothesis for being speculative would be like criticizing a sapling for being short.

Id. The issue, the court explained, was not whether Dr. Carlini had a good hypothesis from a scientific perspective but “the reliability of his opinion from a legal perspective. And what science treats as a useful but untested hypothesis the law should generally treat as inadmissible speculation.” Id. at 18-19.

Judge Sutton concluded:

This is an imperfect system, to be sure. Both sides agree that Mr. Tamraz is a good man who suffers from a terrible disease; we now force him to take the chance of prevailing at trial a second time, with less evidence than before. If he does not, yet it turns out ten years from now that manganese causes his disease, that result will seem unfair. But the alternative route – allowing the law to get ahead of science – would be just as unfair. . . . Rule 702 at all events has drawn the line for us, and we must enforce it. Because this testimony crossed the line, we reverse.

Slip op. at 19 (citations omitted).

As faithful readers of this blog know, we like to take our shots at plaintiffs’ experts, especially paid professional witnesses who deal in junk science and will say anything for a buck. Making snarky comments about these snaky experts is fun, albeit a guilty pleasure. But Judge Sutton’s respectful dismissal of an expert’s testimony as inadmissible is much more satisfying than the snarky stuff and delights the angels of our better nature. Advocates looking for a way to exclude the testimony of a well-credentialed, respected expert would do well to follow Judge Sutton’s opinion.