Torts - Cases, Principles, and Institutions Fifth Edition, 2016a

Witt & Tani, TCPI 6. Causation
not cause the plaintiff’s injury.
Here, by contrast, because the gasoline that has contaminated plaintiffs’ wells was
undeniably the commingled product of numerous manufacturers, there is a good
chance that many of the defendants held liable, if not the majority, actually did cause
plaintiffs’ injury. In this sense, the commingled product theory is closer to
traditional causation than market share liability.
In re MTBE Prods. Liab. Litig., 91 F. Supp. 2d 259 (S.D.N.Y. 2008). While Judge Scheindlin
purports to distinguish between the MTBE cases and the DES cases, it seems that many of the
same practical problems in apportioning fault are still involved. These include the practical
problems identified by Skipworth as a reason not to use market share liability in the lead
poisoning cases. At trial the jury found for the plaintiffs, but did so on grounds that did not
require it to make a decision on the commingled product theory. See In re MTBE Prods. Liab.
Litig., 725 F.3d 65, 117 n. 39 (2d Cir. 2013).
The Substantial Factor Test Revisited
By the 1970s and 1980s, the substantial factor test began to appear outside two-fires type
cases such as Kingston. In 1973, the Fifth Circuit used the substantial factor language to resolve
an indeterminate defendant issue in an asbestos case. The plaintiff had clearly suffered injuries
from his exposure to asbestos, but could not prove by a preponderance of the evidence that any
particular defendant had supplied the asbestos. The Court found that because each defendant had
some role in the cumulative asbestos exposure, each was a “substantial factor” in the injury and
could be held liable. Borel v. Fibreboard Paper Prods. Corp., 493 F.2d 1076, 1094 (5th Cir.
1973). This application of the substantial factor test was adopted by most states and covered toxic
exposure cases including diethylstilbestrol (DES) and environmental damages. See, e.g., Queen
City Terminals v. General Am. Transp. Corp., 73 Ohio St. 3d 609 (1995); Sindell v. Abbott Labs.,
26 Cal. 3d 588 (Cal. 1980). For more, see John D. Rue, Returning to the Roots of the Bramble
Bush: The “But For” Test Regains Primacy in Causal Analysis in the American Law Institute’s
Proposed Restatement (Third) of Torts, 71 FORDHAM L. REV. 2679, 2695 (2003).
The substantial factor test’s role in lowering the plaintiff’s burden of proving causation
has come under significant criticism due to the inherent vagueness of the language and because of
claims that it has imposed additional liability on defendants disproportionate to their actual
contribution to the plaintiff’s injury. Joseph Sanders, Michael D. Williams & William C. Powers,
Jr., Symposium: A Tribute to Professor David Fischer: The Insubstantiality of the “Substantial
Factor” Test for Causation, 73 MO. L. REV. 399 (2008); Gerald W. Boston, Toxic Apportionment:
A Causation and Risk Contribution Model, 25 ENVTL. L.J. 549 (1995).
The Third Restatement of Torts, published in 2003, returned to but-for causation and
removed the substantial factor language, with a separate section imposing liability on defendants
where their conduct was one of multiple sufficient causes. The comments stated that the
“substantial factor” test had not “withstood the test of time, as it has proved confusing and been
misused.” RESTATEMENT (THIRD) OF TORTS: LIAB. FOR PHYS. AND EMOT. HARM, § 26, cmt. J. The
comment backed away from using the substantial factor language to limit liability where the
defendant’s action was not a “substantial” enough cause. It also rejected the use of the substantial
factor language to impose liability where the defendant’s conduct was not a but-for cause, but
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