1. Mass Tort Claims, Product
Testing & Causation Issues
Michael J. McCabe, Jr.,
Ph.D., DABT, ATS
Robson Forensic, Inc.
The Bourse Building, Ste 1000
111 S. Independence Mall East
Philadelphia, PA 19106
(215) 922-1604
www.robsonforensic.com
A.J. de Bartolomeo, Esq.
Gibbs Law Group LLP
One Kaiser Plaza, Ste 1125
Oakland, CA 94612
(510) 350-9711
www.classlawgroup.com
Stanley Goos, Esq.
Daniel I. Jedell, Esq.
Harris Beach PLLC
1o0 Wall Street
New York, NY 10005
(212) 867-0100
www.harrisbeach.com

2. The Daubert Standard
Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993)
 Two touchstones for admissibility: Relevance and Reliability
 Courts undertake “gatekeeping function” regarding expert scientific opinion
testimony, to ensure evidence presented to the jury is reliable and relevant.
 Four factors guide courts in assessing reliability of expert’s methodology:
1) Whether the expert’s methodology has been tested;
2) Whether the technique has been subjected to peer review/publication;
3) Whether there is a known or potential error rate of the methodology; and
4) Whether the technique is generally accepted in the relevant scientific community.
 Rule 702 of the Federal Rules of Evidence

3. The Frye Standard
 Keystone Analysis: Whether the methodology employed is “generally accepted”
in the expert’s particular scientific field
 Underlying notion – the scientists, not the judge, should
determine whether the methodology applied is generally accepted
 Court’s Role as Gatekeeper: to ensure the experts employ the same level of
intellectual rigor in the courtroom that characterizes their scientific practice
in the field
 Goal: exclude junk science – “clearly invalid and unreliable expert opinion”
 State Rules of Evidence (examples):
 New York CPLR § 3101(d)
 California Evidence Code § 801, 802

4. “While the inquiry is a flexible one, the focus must be
solely on principles and methodology, not on the
conclusions that they generate.”
- Chapman v. Procter & Gamble Distributing, LLC (11th Cir. 2014)
“Disagreement among experts is to be expected, since
causation analysis involves professional judgment in
interpreting data and literature. An expert opinion is
precluded when it is reached in violation of generally
accepted scientific principles.”
- Reeps v. BMW of North America LLC, et al. (N.Y. Sup. Ct. 2013)
It’s All About Principles and Methodology…

5. Proving Causation: 2-Step Process
 General Causation:
Whether the substance at issue has the potential to cause plaintiff’s injury
 Plaintiff bears the burden of proof
 Court as gatekeeper, under Daubert or Frye, must determine:
 Does plaintiff’s expert have the requisite qualifications?
 Does plaintiff’s expert employ the necessary methodology?
 Does plaintiff’s expert rely upon sufficiently sound scientific evidence?
 Does plaintiff’s expert comport with the inquiry and factors identified in
Daubert or Frye within the respective areas of expertise?
 Specific Causation:
Whether plaintiff can demonstrate that the substance at issue actually
caused his or her particular injury

6. Goals Under Daubert and Frye
 Plaintiff
To get over the hurdle of establishing general causation, a plaintiff
must present scientifically reliable evidence, not junk science
 General and specific causation cannot be conflated; evidence of a dose-response
relationship (which pertains to to general causation) is distinct from evidence of
the dose the plaintiff was exposed to (which pertains to specific causation)
 Key to establishing general causation: estimating a threshold exposure level
 Threshold exposure level must be established using sound, reliable
methodology, typically via epidemiological studies. However, in the absence of
epidemiology (“epi”) studies regarding the substance at issue (i.e. the
disease/outcome is rare), a plaintiff must still find a reliable way of
demonstrating the requisite dose-response relationship

7. Goals Under Daubert and Frye
 Defendant
Challenge the methodology employed by plaintiff’s expert(s) as
not generally accepted in the scientific community
 Motion in limine to attack plaintiff’s expert’s testimony as inadmissible:
 Plaintiff’s expert failed to use a reliable (primary) methodology to
establish general causation;
 Plaintiff’s expert failed to demonstrate the necessary dose-response
relationship;
 Plaintiff’s expert relies on junk science (i.e. speculative, not subjected
to peer-review or publication, etc.), and thus must be excluded.

8. Expert opinions
based on “junk
science”
are precluded
by the Court
Expert opinions
based on accepted
scientific principles
and sound
methodology are
permitted to go to
the Jury

9. The Expert’s Perspective
Causation Challenge: Multifactorial Basis of Disease
Disease/Disorder/Outcome
Mechanism of Action
In reality  complex
 Environmental Factors (extrinsic)
 Genetic Factors (intrinsic)
 Adaptation & Variability = characteristic of biology
Disease/Outcome
Intrinsic FactorsExtrinsic Factors

10. The Expert’s Perspective
The Scientific Method
1.Define Problem in Form of a Question
2.Gather Information
3.Form a Hypothesis
4.Determine Variables
5.Design Experiment to Test Hypothesis
6.Analyze the Results
7.Draw Conclusions;
Communicate Findings
(replication  validation, falsification)

11. The Expert’s Perspective
Bradford Hill criteria for disease causation
Strength of association; coherence
 epidemiological studies
 OR, RR, SMR > 2.0 (more probable than not)
Temporal association

exposure timing relative to diagnosis
Biological plausibility

mechanism of action
Biological gradient

dose response
* In addition to these 5 factors,
the Bradford Hill criteria also
contain the following 4 factors:
•Consistency
•Specificity
•Experiment
•Analogy

12. The Expert’s Perspective
Epidemiology and Causation
General Causation and Epidemiological Evidence:
 Epidemiology is the study of the incidence of disease in human populations
 Epidemiology expert opinion is commonly admissible if study design is
strong and assumptions are reasonable (equivalence of exposed group to
unexposed group) because data comes from humans.
 Some jurisdictions require an increase in Relative Risk of adverse
effect > 2 (twice as likely as not that the disease is related to exposure)

13. The Expert’s Perspective
Types of Epidemiology Studies

14. The Expert’s Perspective
Hierarchy of Epidemiology Studies

15. The Expert’s Perspective
Are Epidemiology Studies Necessary to
Establish Causation?
Adami et al.,
Toxicological Sciences
2011; 122:223-234

16. The Expert’s Perspective
Case Reports Alone Are Not Persuasive
“Case reports, which anecdotally describe an occurrence, often on
an individual basis, cannot establish general causation ‘because
they simply describe reported phenomena without consideration to
the rate at which the phenomena occur in the general population or
in a defined control group; do not isolate and exclude potentially
alternative causes; and do not investigate or explain the mechanism
of causation.”
- Burst v. Shell Oil Co., 2015 WL 3755953 at *8 (E.D. La 2015)

17. “All things are poison
and nothing is
without poison, only
the dose permits
something not to be
poisonous.”
Paracelsus, c. 1520
Disease/Outcome
Extrinsic Factors Intrinsic Factors

18. General Causation in the Absence of Epi Studies
Chapman v. Procter & Gamble Distributing, LLC (11th Cir. 2014)
Defendant’s motion to exclude testimony of plaintiffs’ causation experts affirmed;
experts did not satisfy any of the reliable primary methodologies for establishing
general causation.
 Neither the experts, nor the scientific support they relied on, determined how
much of the toxin one must be exposed to for how long in order to increase the
risk of developing a neurological deficit, as plaintiff did.
Court: the secondary methodologies relied upon by plaintiffs’ experts are
insufficient proof of general causation.
“… could mislead the jury by causing it to consider testimony that
was insufficient by recognized primary methodologies to prove
using Fixodent causes myelopathy.”

19. General Causation in the Absence of Epi Studies
Wendell v. Johnson & Johnson (N.D. Cal. 2014)
Defendants’ motion for summary judgment granted; establishing general causation
requires, at minimum, admissible evidence to support an inference of “a reasonable
causal connection” between the substance at issue and the development of the
disease/outcome the plaintiff sustained.
 Plaintiff’s causation experts conceded their opinions would not satisfy the
standards required for publication in peer-reviewed medical journals.
 Court rejected experts’ contention that they could not identify any epi studies or
animal studies demonstrating a causal link between plaintiff’s form of cancer
and the drugs prescribed because the particular form of cancer is “exceedingly
rare.”
Court: the difficulty of conducting studies “does not relieve plaintiffs of their
obligation to present evidence of causation,” particularly since > 70% of observed
cases of plaintiff’s form of cancer are idiopathic (no known cause).

20. Using Only Case Reports When Epi Studies Exist
Yates v. Ford Motor Co. (E.D.N.C. 2015)
Defendants’ motion to exclude expert opinion as reliant on case reports denied; case
reports may be used to support other reliable proof
 Defendants: epidemiological (“epi”) studies are necessary predicate to support
case reports; using case reports alone is prejudicial under Fed. R. Evid. 403.
 Case studies are criticized as unreliable evidence of causation because: not
controlled studies; not verified through peer review; fail to exclude other
potential causes; frequently lack analysis.
 However, case reports may provide data that corroborates or supports epi
studies; experts may properly rely on case studies as long as doing so would be
consistent with sound methodology.
Court: Plaintiffs’ experts did not rely solely on case reports; they referred to epi
studies, animal studies, and cellular experiments, among other authorities.

21. Dealing with Inconsistent Epi Studies
In re Actos (Pioglitazone) Products Liability Litigation (W.D. La. 2014)
Defendants’ motion to exclude plaintiffs’ experts’ causation testimony denied; dispute
over whether cancer presenting in ≤ 1 year from first exposure to Actos should be
excluded from or included within consideration from case studies:
 Plaintiffs: improper to exclude cases of bladder cancer development within 1
year of exposure to Actos, as they demonstrate a statistically significant
increase in bladder cancer among those exposed to Actos;
 Defendants: the clinical studies cannot demonstrate causation of bladder
cancer since that type of cancer requires at least 1 year to develop; thus any
cancers presenting within 1 year must be excluded from statistical analysis.
 Court: absent any evidence of biological implausibility, the mere fact that
plaintiffs’ theory is new, and in conflict with the status quo, does not
automatically render such evidence or opinion inadmissible as a
threshold inquiry, if otherwise properly supported and the result of reliable
methodology.

22. Junk Science
Sean R. v. BMW of North America, LLC (N.Y. Ct. App. 2016)
 Denial of plaintiff’s motion to reargue court’s preclusion of causation experts
affirmed; absence of threshold number = failure to establish causation
 General Causation: In the absence of an epi study correlating the exposure to the
toxin to the disorder, the Bradford Hill criteria is not applicable. Moreover,
plaintiff’s experts’ application of Bradford Hill criteria was not sound:
 Scientific sources relied upon dealt with toluene (not gasoline vapor);
 Measurement of strength of association based on case reports (not epi).
 Specific Causation: Methodology rejected; experts concluded the infant was
exposed to enough gasoline vapor to cause birth defects based on his mother’s
reported “symptoms of acute toxicity during exposure.” The experts’ opinion that
the mother inhaled 1,000 ppm of gasoline vapor was extrapolated from studies
concluding that ≥ 1,000 ppm of gasoline vapor concentration is required for those
symptoms to occur immediately.

23. Mass Tort Claims, Product
Testing & Causation Issues
Michael J. McCabe, Jr.,
Ph.D., DABT, ATS
Robson Forensic, Inc.
The Bourse Building, Ste 1000
111 S. Independence Mall East
Philadelphia, PA 19106
(215) 922-1604
www.robsonforensic.com
A.J. de Bartolomeo, Esq.
Gibbs Law Group LLP
One Kaiser Plaza, Ste 1125
Oakland, CA 94612
(510) 350-9711
www.classlawgroup.com
Stanley Goos, Esq.
Daniel I. Jedell, Esq.
Harris Beach PLLC
1o0 Wall Street
New York, NY 10005
(212) 867-0100
www.harrisbeach.com