A 'Masterly' Opinion
on Expert Testimony
By Robert Ambrogi
"Masterly" is the word one blogger used to describe the recent federal appellate opinion overturning
a $21 million jury verdict in a product liability case. Another blogger commended the opinion for adhering
to the "stark and clear text" of Federal Rule of Evidence 702, rather than the more ambiguous language
of the Supreme Court's Daubert decision.
The object of these accolades is the Sept. 8 opinion of the 6th U.S. Circuit Court of Appeals in
Tamraz v. Lincoln Electric Company, in which the court reversed a jury verdict in favor of a welder
who claimed his exposure to manganese caused him to develop parkinsonism.
In a carefully worded opinion, Circuit Judge Jeffrey S. Sutton said that the expert testimony of
the medical doctor who attributed the welder's disease to his manganese exposure fell on the wrong side
of "the often-elusive line between admissible opinion and inadmissible speculation."
While the court was careful to praise the expert as intelligent and knowledgeable, it said that his
testimony concerning causation was at best a working hypothesis, not admissible scientific knowledge.
"Because the 'knowledge' requirement of Rule 702 requires 'more than subjective belief or unsupported
speculation,'" Judge Sutton wrote, "the testimony should have been excluded."
Robert J. Ambrogi
is a Massachusetts lawyer who represents clients at the intersection of law, media and technology. A
news media veteran, he is the only person ever to hold the top editorial positions at the two leading
national U.S. legal newspapers, the National Law Journal and Lawyers Weekly USA. He is also
internationally known for his writing and blogging about the Internet and technology.
Adding to the significance of the case is that it was one of the first to go to trial of several against
manufacturers of welding supplies that were consolidated as multidistrict litigation in the Northern
District of Ohio. As the 6th Circuit's opinion noted, this case was seen as a "bellwether … to guide
the resolution of the other cases."
Disagreement over Diagnosis
The plaintiff, Jeff Tamraz, worked as a welder in California from 1979 to 2004. Beginning in 2001,
he started to suffer symptoms of parkinsonism, including tremors, drooling and impaired coordination.
Believing that his condition was due to his exposure to manganese fumes in welding products, he sued
At trial, the dispute focused not on whether Tamraz suffered from parkinsonism, but on its type.
His contention was that he had manganism, a form of parkinsonism caused by exposure to manganese. The
defense contended that he had Parkinson's Disease, a form of parkinsonism for which the cause is unknown.
The symptoms of the two forms of the disease are similar but not identical., a form of parkinsonism
caused by exposure to manganese. The defense contended that he had Parkinson's Disease, a form of parkinsonism
for which the cause is unknown. The symptoms of the two forms of the disease are similar but not identical.
At the conclusion of the trial, the jury found against all five defendants on claims of strict liability
and negligent failure to warn. The jury awarded Tamraz $17.5 million in compensatory damages and his
wife $3 million for loss of consortium.
Key to the verdict, the 6th Circuit found, was the testimony of the plaintiff's treating neurologist.
Although several doctors testified as expert witnesses, it was the neurologist's evaluation of causation
that substantially swayed the jury, the court said.
In its analysis of the case, the court focused on the evidence regarding the etiology – or causation
– of Tamraz's parkinsonism. The neurologist testified that Tamraz's symptoms resembled those of Parkinson's
Disease. But he hypothesized that Tamraz might have had a genetic predisposition to Parkinson's that
manganese could have triggered, even in lower levels than are necessary to cause manganism..
This testimony should not have been admitted, the 6th Circuit said, because the expert went beyond
the boundaries of what is allowed under Rule 702. "The etiological component of this conclusion – the
'manganese-induced' part – was at most a working hypothesis, not admissible scientific 'knowledge,'"
Judge Sutton wrote. "Because the 'knowledge' requirement of Rule 702 requires 'more than subjective
belief or unsupported speculation,' … the testimony should have been excluded."
Even though the expert's hypothesis was plausible and "may even be right," it was nonetheless untested
and required a leap of faith, the court said. "That manganese could cause Parkinson's Disease in someone
like Tamraz does not show that manganese did cause Tamraz's Parkinson's Disease."
Judge Sutton was careful to say that the court's opinion should not be read as a criticism of the
expert for presenting the sort of hypothesis that plays a valuable role in advancing medical science.
But the law must follow science, not get ahead of it, he noted.
"The issue is the reliability of his opinion from a legal perspective," Judge Sutton explained. "And
what science treats as a useful but untested hypothesis the law should generally treat as inadmissible
Dissent Sidesteps Rule 702
In a dissenting opinion, Judge Boyce F. Martin Jr. criticized the majority for its failure to defer
to the trial judge's "gatekeeper" finding that the expert's testimony was admissible. The trial judge
was correct to have admitted the testimony under the standards set out by the Supreme Court in Daubert,
Judge Martin argued.
"While [the neurologist] testified that he was not able to point to a specific study showing that
manganese exposure caused Parkinson's Disease, his testimony was supported by his own general experience
and knowledge …, and theoretical medical writing that explored the connection between manganese exposure
and Parkinson's Disease," Judge Martin explained.
David E. Bernstein, a professor at George Mason University School of Law and a nationally recognized
expert on the admissibility of expert testimony, contended that the dissent is wrong in its reliance
on Daubert in place of Rule 702.
"Rule 702, promulgated in 2000, and not the more ambiguous Daubert or Kumho Tire opinions, decided
in 1993 and 1999 respectively, is what dictates the scope of admissible expert testimony," Bernstein
wrote in a post at the blog The Volokh Conspiracy. "Any interpretation of Daubert, Kumho Tire, or the
1997 Joiner case that conflicts with the subsequent statute, Rule 702, is legally incorrect."
No Snarky Stuff Here
Meanwhile, James M. Beck, the Dechert LLP lawyer who writes the blog Drug and Device Law, praised
the majority opinion not only for its reasoning, but also for its craftsmanship.
"Every once in a great while, we read an opinion that stands out as an example of judicial craftsmanship,"
Beck wrote at his blog. "The facts and issues are explained in clear, lively prose. The reasoning is
careful and thorough, leading inevitably to undeniable conclusions."
Beck was particularly appreciative of the respect the opinion's author showed to the parties in the
case and to the expert whose testimony was under examination. Conceding that, as a blogger, he sometimes
takes pleasure in "making snarky comments" about experts, he commended Judge Sutton for taking the high
road in the opinion.
"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," Beck said. "Advocates looking for
a way to exclude the testimony of a well-credentialed, respected expert would do well to follow Judge
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