By Dan Jaffe on July 8, 2016

New York’s highest court, the Court of Appeals, recently affirmed lower courts’ orders excluding the causation testimony of two experts under the Frye Rule [Frye v United States, 293 F. 1013 (DC Cir. 1923)]. Sean, R. v. BMW of N. Am., LLC, 26 N.Y.3d 801, 48 N.E.3d 937, 28 N.Y.S.3d 656 (2016).

In Sean R., Plaintiff was born May 1992 with severe mental and physical disabilities which he claimed were caused by in utero exposure to unleaded gasoline vapor which in turn was caused by a defective fuel hose in his mother’s BMW.  Plaintiff’s mother became pregnant with Plaintiff in July/August of 1991.  After she first smelled the gasoline, Plaintiff’s mother had driven the BMW a total of 6,458 miles over an eight month period before the split fuel hose was fixed.

Plaintiff offered two primary causation experts to testify that Plaintiff’s in utero exposure to gasoline vapor proximately caused his birth defects.  Both experts concluded that Plaintiff’s mother inhaled 1,000 parts per million (ppm) of gasoline vapor based on testimony that “she and others experienced symptoms of acute toxicity during exposure, such as headache, nausea, and irritation of the throat and mucous membranes.”  As support for this conclusion they cited controlled studies, “…for symptoms such as these to occur immediately, a gasoline vapor concentration of at least 1,000 ppm… is required.”  The experts also relied on published criteria to conclude that unleaded gasoline vapor is capable of causing the types of birth defects Plaintiff suffered.  Finally, after purporting to rule out other possible causes, they concluded the mother’s “high peak exposure[ ]” to gasoline  vapor during the first trimester of her pregnancy  was the most likely cause of Plaintiff’s injuries.

The New York Court of Appeals held that this opinion testimony should be excluded. First, in toxic tort cases expert causation opinion must set forth (1) a plaintiff’s exposure to a toxin, (2) that the toxin is capable of causing the particular injuries plaintiff suffered (general causation) and (3) that the plaintiff was exposed to sufficient levels of the toxin to cause such injuries (specific causation).  While precise quantification of the level of exposure is not always necessary, plaintiff must offer evidence from which the factfinder can conclude plaintiff was exposed to levels that are known to cause the injury type that plaintiff claims to have suffered.

Second, the causation expert must not only establish that plaintiff was exposed to a level of a toxin capable of causing his injuries, but must do so through methods “found to be generally accepted as reliable in the scientific community.” In New York, the Frye test asks whether the accepted techniques, when properly performed, generate results accepted as reliable within the scientific community generally.  Although unanimity is not required, the proponent must show “consensus in the scientific community as to [the methodology’s] reliability.”

The Sean R. plaintiff failed to show that the methodology used was accepted by a consensus of the scientific community as reliable. The controlled studies cited by Plaintiff’s experts did not support the inverse approach employed by Plaintiff’s experts in this case—working backwards from verbal reports of occasional symptoms to divine a purported exposure level of “1,000 ppm” from an unmeasured and otherwise unknown concentration of gasoline vapor. To the contrary, the cited controlled studies were all based on precisely measured levels of toxins and the reported symptoms they caused. Moreover, Plaintiff’s experts did not identify any study, report, article or opinion that admitted or employed such inverse methodology, let alone a “consensus” as to its reliability. Plaintiff failed to show that a “symptom-threshold” methodology, unlike the odor threshold methodology, has been generally accepted in the scientific community.

Expert causation testimony concerning toxic exposure in New York must be based upon a reliable methodology applied to the facts of the case in order to be admissible.  This is essential in New York under the Frye test as well as in Federal practice under the Federal Rules of Evidence, Rule 702(c).