Page 221 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

188 SECTION | I General

VetBooks.ir Courts generally agree that, whenever there are different causation should be proven first, then the specific causa-
The order of proving causation is important. General
causes for the plaintiff’s disease, an expert must perform a
See
tion differential diagnosis analysis. In virtually all cases,
differential diagnosis before testimony will be admitted.
Gianelli.
Courts accept the general validity of the technique differential diagnosis does not provide general causation—
US v Downing 44
of differential diagnosis. An expert opinion it can only provide specific causation. This may be part
based on a properly performed differential diagnosis analy- of the reasoning that argues that epidemiological data is
Westberry at 263
sis is not likely to be inadmissible. More spe- rarely determinative in a specific causation analysis, and is
cifically, “[t]o the extent that a doctor utilizes standard most commonly used in the general causation argument.
diagnostic techniques in gathering this information, the To show that said exposure was the actual cause of
more likely we are to find that the doctor’s methodology is the injury, toxic tort plaintiffs must prove the admissibil-
reliable.” In re Paoli, at 758. ity of their expert testimony in both general causation and
Put differently, “[a]n expert who opines that exposure to specific causation context by a preponderance of
a compound caused a person’s disease engages in deductive proof. Daubert at 593 A successful plaintiff must not only
clinical reasoning. .. . The opinion is based on an assess- show that, more likely than not, the substance can cause
ment of the individual’s exposure, including the amount, the injury in question, but also that, more likely than not,
the temporal relationship between the exposure and disease, the plaintiff’s specific injury was in fact caused by the
and other disease-causing factors. This information is then substance. DeLuca, Ronald J. Allen
compared with scientific data on the relationship between A Daubert analysis should be performed. In fact, “a trial
exposure and disease. The certainty of the expert’s opinion court that fails to justify its decision not to use Daubert fac-
depends on the strength of the research data demonstrating tors risks reversal.” Black v Food Lion Daubert factors may be
a relationship between exposure and the disease at the dose used when assessing the admissibility of clinical medical
in question and the absence of other disease causing factors testimony. Moore This opinion is because reliable opinions
(also known as confounding factors).” Reference guide at are reached using the “methods and procedures of science.”
422 423.
See also Joseph Sanders. Scientific validity is the foundation of “evidentiary
However, simply stating that a differential diagnosis reliability” Daubert at 590 See also, Bert Black et al.
was performed is not enough. This issue was discussed in So the expert in our case, must not only rule-in the
Viterbo: chemical added to the feed additive as the cause of the
clinical signs and lesions observed, but must also rule out
We do not hold, of course, that admissibility of an expert
other diseases that cause these clinical signs or lesions in
opinion depends upon the expert disproving or discrediting
that specific animal to arrive at specific causation.
every possible cause other than the one espoused by him.
Here, however, Dr. Johnson has admitted that Viterbo’s
symptoms could have numerous causes and, without support
APPLICATION OF DAUBERT
save Viterbo’s oral history, simply picks the cause that is
most advantageous to Viterbo’s claim. Indeed, Dr. Johnson’s IN TOXICOLOGY CASES
testimony is no more than Viterbo’s testimony dressed up and
The application of these legal rules to specific toxicology
sanctified as the opinion of an expert. Without more than
cases may be useful. Testimony may be weakened if there
credentials and a subjective opinion, an expert’s testimony Goebel, 2000.
is no Daubert inquiry at all.
that “it is so” is not admissible. Viterbo v Dow Chemical
The differential diagnosis portion of analyzing specific
This formulation is repeated by Judge Becker in causation is important. Expert testimony from a forensic
United States v. Downing. toxicologist has been properly excluded for insufficient
proof to rule in the chemical in question and to rule out
The process of differential diagnosis is undoubtedly important Wills,2004.
other diseases. The testimony of a toxicologist
to the question of “specific causation.” If other possible
was properly excluded because the toxicologist was not a
causes of an injury cannot be ruled out, or at least the proba-
medical doctor and therefore not qualified to offer reliable
bility of their contribution to causation minimized, then the Plourde,2003.
differential diagnosis analysis. On the other
“more likely than not” threshold for proving causation may
hand, testimony was properly allowed from two marine
not be met. But, it is also important to recognize that a funda-
biologists who each performed a differential diagnosis anal-
mental assumption underlying this method is that the final,
ysis in a case involving marine animals (Clausen, 2003).
suspected “cause” remaining after this process of elimination
Dose is important in toxicology cases. Testimony of a
must actually be capable of causing the injury. That is, the
treating physician, toxicologist and industrial hygienist
expert must “rule in” the suspected cause as well as “rule
out” other possible causes. And, of course, expert opinion on
this issue of “general causation” must be derived from a sci- 44. See generally, Raynor v. Merrell Pharmaceuticals, 101 F.3d 129,
138-39 (D.C. Cir. 1996). See also, Kelly, Grimes, Rutigliano, Hall,In re
entifically valid methodology. Cavallo v Star Enterprise
Breast Implant, National Bank of Commerce and Wynacht.