Complex Litigation

A ‘Refresher’ for Expert Battles in 2018

By Michael Hoenig - New York Law Journal - December 8, 2017

Year 2018 is virtually upon us. Is the reader fully prepared on the law for expert reliability battles sure to come? New York state courts approach gatekeeping of experts somewhat differently than federal judges. The “Frye-plus” analysis used in state court can be a tad complicated for the unprepared advocate. This “refresher” discussion tries to make the task easier because the modern interface of Frye gatekeeping (for novel scientific issues) and judicial screening of experts’ reliability in all other cases is reflected in four significant N.Y. Court of Appeals decisions. They are People v. Wesley, 83 N.Y.2d 417 (1994); Parker v. Mobil Oil, 7 N.Y.3d 434 (2006); Cornell v. 360 W. 51st Realty, 22 N.Y.3d 762 (2014); Sean R. v. BMW of North America, 26 N.Y.3d 801 (2016).

‘People v. Wesley’

People v. Wesley, 83 N.Y.2d 417 (1994) restated New York’s modern version of the Frye rule. Decided in March 1994, with only five judges participating, the issue was whether DNA profiling (in 1988 and 1989), as novel scientific evidence, was generally accepted by the relevant scientific community to be admitted against the defendant in a murder and rape case. Three judges held “yes.” Chief Judge Judith S. Kaye (joined by Judge Carmen Beauchamp Ciparick) issued a separate concurring opinion “out of concern, for future cases, that the principles governing admission of novel scientific evidence be correctly articulated and applied.”

Wesley established that the Frye inquiry, the so-called “general acceptance” test for novel scientific evidence, is a quest for reliability. All the judges agreed that, after the Frye question, there is a “foundation assessment” where the focus moves from general reliability to specific reliability of the foundation, a preliminary matter of law. Chief Judge Kaye called it an inquiry going to admissibility, not simply its weight. It is an issue of law for the judge. If it is a “trustworthiness” issue, it is assessed by the court. Infirmities in collection and analysis not affecting trustworthiness go to “weight,” to be assessed by the jury. Wesley thus says there are separate or distinct reliability quests, headlined by the words, Frye (general acceptance test) and “Foundation.” Further, the foundational inquiry is employed in all science cases, not just “novel” science cases. Thus, trial courts are required to gatekeep for reliability in science cases not governed by Frye as well.

‘Parker v. Mobil Oil’

The court’s Oct. 17, 2006 decision in Parker v. Mobil Oil, 7 N.Y.3d 434 (2006) is informative on the sophisticated toxic tort arena as well as the gatekeeping task in other science settings. First, the facts in a nutshell. Mr. Parker, a gas station attendant for some 17 years, developed a form of leukemia (AML) his experts attributed to benzene exposure through inhalation of gasoline fumes and through skin contact with gasoline. He sued Mobil Oil and other defendants for toxic consequences and failure to warn. The parties’ experts disputed what the specific cause of Mr. Parker’s leukemia was. Defendants moved to preclude Mr. Parker’s expert testimony on the issue of medical causation. Defendants contended plaintiffs’ expert testimony regarding causation was scientifically unreliable under the Frye standard. Defendants also moved for summary judgment dismissing all claims because of the inappropriate causation evidence. Neither side requested a Frye hearing.

The trial court denied defendants’ motion. The Appellate Division reversed, however, holding that since Mr. Parker’s experts neither quantified plaintiff’s actual exposure nor the threshold required, they could not show that Mr. Parker’s exposure exceeded the minimum disease-causing level. The causation opinions were therefore deemed speculative.

The Court of Appeals affirmed the dismissal but on the ground that plaintiff’s experts, although highly qualified in their respective fields, “failed to demonstrate that exposure to benzene as a component of gasoline caused [Mr.] Parker’s AML.” The dispute was not whether there was an associational relationship between benzene exposure and the risk of developing AML. The key issue was the relationship, if any, between exposure to gasoline containing benzene as a component and the disease. The experts failed to make this connection. Thus, the experts’ opinions were properly excluded. Despite affirming the dismissal, the court rejected the Appellate Division’s approach on a need for precise quantification of the dose-response relationship in all cases. The court then referred to “several other ways an expert might demonstrate causation.”

Parker announced a number of other important gatekeeping principles. The court explained that when “novel scientific evidence” is introduced, there must be a determination of its reliability. The Frye “general acceptance” test asks “whether the accepted techniques, when properly performed, generate results accepted as reliable within the scientific community generally.”

However, said the court, the Frye inquiry is “separate and distinct from the admissibility question applied to all evidence—whether there is a proper foundation—to determine whether the accepted methods were appropriately employed in a particular case.” Thus, the focus moves “from the general reliability concerns of Frye to the specific reliability of the procedures followed to generate the evidence proffered and whether they establish a foundation for the reception of evidence at trial.” In Parker, there was no particular novel methodology at issue. The inquiry was more akin to “whether there is an appropriate foundation for the experts’ opinions, rather than whether the opinions are admissible under Frye.” The answer was “no”.

The federal Daubert gatekeeping standard was mentioned. See generally, Fed. R. Evid. 702; Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993); General Elec. Co. v. Joiner, 522 U.S. 136 (1997); Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999). The Court of Appeals, when analyzing federal case law on how much precise exposure information a toxic tort plaintiff needs to prove, stated in its footnote 4: “We recognize that these cases employ a Daubert analysis. However, they are instructive to the extent they address the reliability of an expert’s methodology.” Therefore, it may be feasible for counsel to use Daubert admissibility criteria in connection with the foundational reliability inquiry.


In 2014, the Court of Appeals issued its key decision in Cornell v. 360 W. 51st St. Realty, 22 N.Y.3d 762 (2014), again offering detailed guidance to bench and bar on a variety of expert issues. Plaintiff was a resident of a Manhattan building which developed mold as a result of demolition and construction work in the basement. She became physically ill, attributing a variety of ailments to exposure to mold and other harmful substances. Defendant moved for summary judgment specifically seeking dismissal of the complaint to the extent plaintiff alleged mold-induced personal injuries. Defendant urged that Cornell could not prove that mold can cause the type of injuries she alleged (general causation), or that apartment mold caused her specific injuries (specific causation).

Defendant’s expert opined with reasonable medical certainty that there was “no relationship between the medical problems experienced by Ms. Cornell and exposure to molds.” On “general causation,” he relied on the position paper of the American Academy of Allergy, Asthma and Immunology (AAAAI) which he referred to as “the current ‘state of the art’ and widely accepted as authoritative.” Cornell also could not demonstrate “specific causation” for some seven itemized reasons quoted by the court in its opinion. One of these was that plaintiff’s complained-of medical problems “are common in the human population regardless of indoor exposure to molds.”

Plaintiff’s expert opined the illness was “undeniably caused by exposure to an unusual mixture of atypical microbial contaminants.” He cited a number of studies saying that various mold byproducts “may” have adverse effects to humans; that the “risk” of certain conditions was higher in damp homes; there is sufficient evidence of “associations” of building dampness with the presence of mold; there is “suggestive evidence of associations” with shortness of breath and development of asthma; and that the existence of recent studies “support the link” between a damp indoor environment, mold growth and upper airway irritant symptoms.

Ultimately, the Court of Appeals held that the expert’s conclusions on general and specific causation were insufficient. The court reiterated its established principles regarding Frye and Parker. Although Frye focuses on principles and methodologies, these are “not entirely distinct from one another.” Even if an expert is using reliable principles and methods and is extrapolating from reliable data, a court may still exclude the expert’s opinion if “there is simply too great an analytical gap between the data and the opinion proffered.” Thus, an opinion connected to existing data “only by the ipse dixit of the expert” may be excluded. The expert’s conclusion, too, has to be reliable. The court reiterated that the precept has sometimes been expressed in terms of the “general foundation inquiry applicable to all evidence” (citing Parker and Wesley).

The studies cited by plaintiff’s expert merely spoke in terms of “risk,” “linkage” and “association”—“not causation.” He thereby departed from the generally accepted methodology for evaluating epidemiological evidence. The expert also did not reliably show the necessary specific causation. As Parker explains, an opinion on causation should set forth not only a plaintiff’s exposure to a toxin and that the toxin is capable of causing the particular illness (general causation) but also that plaintiff was “exposed to sufficient levels” of the toxin to cause the illness (specific causation). Here plaintiff’s expert did not identify the specific disease-causing agent other than to vaguely describe it as “an unusual mixture of atypical microbial contaminants.”


Sean R. v. BMW of North America, 26 N.Y.3d 801 (2016) involved a claim that a youngster’s mental and physical disabilities were caused by in utero exposure to unleaded gasoline vapor attributable to a defective gas hose in the pregnant mother’s BMW vehicle. New York’s highest court provided the trial bench and bar with yet more guidance about what is needed in the way of reliable expert testimony in a toxic tort claim.

The timeline underlying the claim was as follows. In May 1989, the father purchased a new BMW 525i for his wife. In the spring of 1991 she began to notice a smell of gasoline that “came and went.” When the windows were closed, the strong odor caused headaches, dizziness and throat irritation.

In July or August 1991, the wife became pregnant with plaintiff. The husband took the car to the dealer and a split fuel hose was discovered. Plaintiff was born in May 1992 with severe mental and physical disabilities. Subsequent testing revealed the child had, among other things, spastic quadriparesis (a form of cerebral palsy), developmental delays, ventricular asymmetry, aortic stenosis and impaired vision function. Two years later, BMW recalled the vehicles due to defects in the feed fuel hoses. The recall report noted that customers had associated the defect with a “conspicuous fuel odor.”

Plaintiff’s primary causation experts were prepared to testify that the in utero exposure to gasoline vapor proximately caused the birth defects. BMW moved to preclude these causation experts from testifying at trial. Alternatively, defendant asked for a Frye hearing to determine whether the experts were reaching novel conclusions and not using generally accepted principles and methodologies. After reviewing lengthy submissions and supplemental expert reports the trial court precluded the causation experts. The Appellate Division affirmed but certified the question to the Court of Appeals.

The state’s highest court held that the experts should be precluded from testifying. The court explained that in toxic tort cases an expert opinion on causation must set forth (1) a plaintiff’s exposure to a toxin, (2) that the toxin is capable of causing plaintiff’s particular injuries (general causation) and (3) that the plaintiff was exposed to sufficient levels of the toxin to cause such injuries (specific causation). The expert must establish such exposure levels “through methods ‘found to be generally accepted as reliable in the scientific community’.” This “general acceptance” requirement, also known as the Frye test, “governs the admissibility of expert testimony in New York.”

In a footnote, the court explained that its analysis and holding were limited to the Frye “general acceptance” inquiry due to the procedural posture of the case. Thus, the court expressed no opinion on the “separate and distinct” question of whether there was a proper foundation for the experts’ opinions.” The Frye analysis was dispositive. The experts did not show “consensus in the scientific community as to the [methodology’s] reliability.” Statistical literature noting “associations” or murky “connections” between a toxin and a disease do not reliably establish either general or specific causation.


The Court of Appeals made it clear that questions regarding reliability of experts’ testimony require diligent policing by courts. The basic rules seem simple enough. If “novel” scientific evidence is involved, the court applies the Frye “general acceptance” test to determine “whether the accepted techniques, when properly performed, generate results accepted as reliable within the scientific community generally.” If the answer is “no,” the testimony has flunked and must be precluded or excluded. If the answer is “yes,” the proponent of the novel scientific testimony has survived the threshold test but still has to get past the admissibility “gate.” The evidence must meet a second, “foundational reliability” inquiry. This second admissibility standard applies to all expert testimony, not just “novel” scientific evidence. If attorneys for plaintiffs and defendants diligently study the four key decisions discussed here, they will be equipped to structure, defend or attack expert testimony in the reliability battles sure to come.

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