State Variations on the Daubert Theme:





Jerry C. Parker


Reid Wm. Martin





            Following the decision in Daubert v. Merrell Dow Pharmaceuticals, Inc.,[1] several opinions delivered by the Supreme Court of Texas have interpreted and expanded Daubert by promulgating new and specific standards regarding its use in that state.  The purpose of this article is to discuss the most significant Texas Supreme Court opinions since Daubert relating to the admissibility and use of expert testimony.  These include: E.I. du Pont de Nemours Company v. Robinson, Broders v. Heise, United Blood Services v. Longoria, Merrell Dow Pharmaceuticals, Inc. v. Havner, Maritime Overseas Corp. v. Ellis, and finally, Gammill v. Jack Williams Chevrolet, Inc.  All of these cases address the issue of how Texas courts should utilize the four factors[2] articulated by Justice Blackmun in Daubert.  The opinions also advance specific criteria unique to Texas.




            E.I. du Pont de Nemours & Co. v. Robinson[3] was the first of several Texas Supreme Court cases to apply Daubert factors.  However, the decision offered two additional factors for consideration when determining the admissibility of expert scientific testimony.  In Robinson, a horticultural expert offered testimony that pecan trees were damaged by one of Du Pont’s products.  The trial court ruled that the proffered testimony was not admissible since the foundation of the expert’s underlying methodology was unreliable.  The court of appeals reversed this ruling, holding that the jury should be allowed to determine both the weight and credibility of an expert’s testimony.  The Texas Supreme Court then reversed the court of appeals; in doing so, it announced the “Texas version” of Daubert, which includes a six-part test for evaluating the reliability of scientific expert testimony.

            The Supreme Court of Texas essentially adopted Justice Blackmun’s “general observations” in Daubert, ruling that Texas trial courts should consider these factors when evaluating expert scientific testimony.  However, the Robinson court then added two other factors to the Daubert “general observations.”  These can be summarized as follows: (1) the extent to which the technique relies upon the subjective interpretation of the expert; and (2) the non-judicial uses which have been made of the theory or technique. These factors are not exclusive in Texas; they have been termed the “Robinson reliability factors.”  In combination, they were outlined in Robinson as follows:


(1)       [T]he extent to which the theory has been or can be tested;

(2)       [T]he extent to which the technique relies upon the subjective interpretation of the expert;

(3)       [W]hether the theory has been subjected to peer review and/or publication;

(4)       [T]he technique’s potential rate of error;

(5)       [W]hether the underlying theory or technique has been generally accepted as valid by the relevant scientific community; and

(6)       [T]he non judicial uses which have been made of the theory or technique.[4]




            The Texas Supreme Court revisited the Daubert analysis in Broders v. Heise,[5] applying Daubert to the question whether all doctors are qualified to testify about any medical issue.  At trial, an emergency room physician sought to provide expert causation testimony regarding a brain injury.  The trial court refused to allow the physician to offer his causation opinion because it determined that he was not competent to testify on causation relative to the alleged brain injury.  The court of appeals reversed the trial court, explaining that the emergency room physician possessed knowledge and skills not possessed by people generally. Thus, it held that the physician was competent to offer an expert opinion under Texas Rule of Civil Procedure 702.  The Supreme Court of Texas reversed the judgment of the court of appeals, however, because it determined that the trial court did not abuse its discretion in excluding the proposed testimony.

            The high court found that all doctors are not qualified to provide expert testimony with regard to every medical question.  The Broders court emphasized that “[w]hat is required is that the offering party establish that the expert has ‘knowledge, skill, experience, training or education’ regarding the specific issue before the court which would qualify the expert to give an opinion on that particular subject.” [6]  The Broders court also pointed out that when “a subject is substantially developed in more than one field, testimony may come from a qualified expert in any of those fields.”[7] Thus, the Broders case provides authority to challenge a proposed expert based upon his or her specific expertise.   It may be utilized as well to support the use of an expert, depending upon his or her background and the specific area of expertise.





            In a per curium opinion in United Blood Services v. Longoria,[8] the Texas Supreme Court once again affirmed a trial court’s exclusion of proposed expert testimony. The decision strengthened the trial court’s discretionary authority when acting as the gatekeeper of evidence.[9] In Longoria, the trial court determined that a proposed non-physician expert, who did not hold himself out as an expert in the subject field and never worked or engaged in any study in that field, was not competent to testify as proposed.  The supreme court held that “[w]hether a witness is qualified to offer expert testimony is a matter committed to the trial court’s discretion.”  Furthermore, a contrary opinion by the court of appeals on the expert’s qualifications would not substitute for the trial court’s earlier ruling.[10]





            The decision in Merrell Dow Pharmaceuticals v. Havner[11] is the most significant Texas Supreme Court opinion to follow Robinson. It focused on whether the underlying scientific bases relied upon by the proposed expert in that case were “reliable.” In Havner, the Texas Supreme Court extended the Daubert/Robinson standards to its “no evidence” review, thereby securing a method of supreme court review in all cases involving the trial court’s exclusion of expert testimony.  The Havner decision is noteworthy because it extended the Texas Supreme Court’s limited ability to review decisions relating to the admissibility of evidence.  In short, the supreme court determined that the analysis of expert testimony admissibility involves a question of legal sufficiency and thus solidified its role in reviewing this evidentiary ruling.

            The Havner court also made two important findings that modified Texas’ application of the Daubert analysis.  First, the court decided that the bare causation opinion of a proposed expert, who is qualified under Texas Rule of Civil Procedure 702, constitutes “no evidence” by itself.  Second, the Havner court offered two specific circumstances when a proposed expert’s opinion would be considered “no evidence” by the court:


(1)            If the foundational data underlying opinion testimony are unreliable; and

(2)            [I]f the expert drew conclusions from that data based on flawed methodology.[12]


The Havner court’s Daubert analysis occurred in the context of toxic tort litigation, and was specifically relevant to the concepts of “general causation” and “specific causation.”  The Texas Supreme Court distinguished these important concepts, holding that “[g]eneral causation is whether a substance is capable of causing a particular injury or condition in the general population, while specific causation is whether a substance caused a particular individual’s injury.”[13] Specific causation in environmental litigation traditionally had been proved in Texas through evidence of direct experiments and epidemiological studies.

            In Havner, the Texas Supreme Court noted that the plaintiffs relied primarily on epidemiological studies, but also relied on in vivo animal studies and in vitro animal studies, as well as direct testimony of causation from medical experts.  Within that context, the court established new minimum requirements concerning the statistical “relative risk” necessary to create a fact issue: a plaintiff’s epidemiological proof must show more than a “doubling of the risk” to avoid being automatically adjudged “no evidence.”[14]  However, even that may not be sufficient, since other factors must be considered initially: “We do not hold, however, that a relative risk of more than 2.0 is a litmus test or that a single epidemiological test is legally sufficient evidence of causation.  Other factors must be considered.”[15]  The court then observed: “[E]pidemiological studies only show an association.  There may in fact be no causal relationship even if the relative risk is high.”[16]  Explaining further, the court said: “[B]ias can dramatically affect the scientific reliability of an epidemiological study.”[17]  In addition, the court noted:

We draw no conclusions from any of the foregoing articles other than to point out that there are a number of reasons why reliance on a relative risk of 2.0 as a bright-line boundary would not be in accordance with sound scientific methodology in some cases.  Careful exploration and explication of what is reliable scientific methodology in a given context is necessary.[18]


Finally, the Havner court remarked: “It must be reiterated that even if a statistically significant association is found, the association does not equate to causation.”[19]

            In that regard, the confidence interval cannot cross 1.0 for relative risk evidence to raise a fact issue in Texas courts.  As the Texas Supreme Court has explained, “[a] confidence level can be used in epidemiological studies to establish the boundaries of the relative risk.  These boundaries are known as the confidence interval.”[20] The court also noted that “[a] confidence interval shows a ‘range of values within which the results of a study sample would be likely to fail if the study were repeated numerous times.’”[21]

To further explain the range of values concept, the court wrote: “If, based on a confidence level of 95%, a study showed a relative risk of 2.3 and had a confidence interval of 1.3 to 3.8, we would say that, if the study were repeated, it would produce a relative risk between 1.3 and 3.8 in 95% of the repetitions.”[22]  Finally, the supreme court cautioned that “if the interval includes the number 1.0, the study is not statistically significant or, said another way, is inconclusive.”[23]

            The court continued that a statistical significance level of 95% or higher is necessary for a plaintiff’s epidemiological evidence to constitute more than no evidence, although different statistical significance levels are often used by statisticians.   In this case, the court selected the 95% statistical significance level as the minimum threshold in order for epidemiological studies to constitute “some evidence” of causation. The court explained the significance of this approach: “[t]he generally accepted significance level or confidence level in epidemiological studies is 95%, meaning that if the study were repeated numerous times, the confidence interval would indicate the range of relative risk values that would result 95% of the time.”[24] In adopting this norm, the court cautioned that “[w]e should not widen the boundaries at which courts will acknowledge a statistically significant association beyond the 95% level to 90% of lower values.”[25]

            Furthermore, the supreme court noted that the dosage levels in epidemiological studies must be similar to those of the plaintiff for the studies to constitute “some evidence” of causation:

To raise a fact issue on causation and thus to survive legal sufficiency review, a claimant must do more than simply introduce into evidence epidemiological studies that show a substantially elevated risk.  A claimant must show that he or she is similar to those in the studies.  This would include proof that the injured person was exposed to the same substance, that the exposure or dose levels were comparable to or greater than those in the studies, that the exposure occurred before the onset of injury, and that the timing of the onset of injury was consistent with that experienced by those in the study.[26]


In toxic tort matters, the court now requires that “if there are other plausible causes of the injury or condition that could be negated, the plaintiff must offer evidence excluding those causes with reasonable certainty.”[27]





            In Maritime Overseas Corp. v. Ellis,[28] the Texas Supreme Court held that Daubert/Robinson/Havner challenges must be made in timely fashion at the trial court level. Specifically, errors raised for the first time on appeal, based upon Daubert and its Texas progeny, are deemed waived.  While there does not appear to be a single occasion or specific time to assert an objection to a proposed expert’s testimony, the preferred practice is to request a “gatekeeper hearing” prior to presentating  the intended witness before the jury.  Many Texas trial courts conduct such hearings with live testimony prior to trial. This practice is extremely helpful for trial preparation and verdict exposure evaluations.





            In 1998, the Texas Supreme Court decided Gammill v. Jack Williams Chevrolet, Inc.,[29] holding that an expert who offers testimony about mechanical engineering is subject to challenge under the Robinson reliability factors. The court noted, however, that the Daubert and Robinson reliability factors would not apply to the mechanical engineering field as a general rule.  Justice Hecht distinguished general relevance and reliability requirements vis á vis applicability of the Daubert and Robinson reliability factors for scientific evidence as follows:

All expert testimony should be shown to be reliable before it is admitted.  That said, it is equally clear that the considerations listed in Daubert and in Robinson for assessing the reliability of scientific evidence cannot always be used with other kinds of expert testimony. . . .  In determining whether Daubert applies to particular expert testimony, some courts have confused two aspects of Daubert: on the one hand, the construction of Rule 702 to require that expert testimony be reliable and relevant, and on the other hand, the considerations to be used in determining the reliability of scientific opinion.[30]


The Texas Supreme Court emphasized that this distinction applies with equal force to the Robinson reliability factors.  The United States Supreme Court likewise addressed this distinction in Kumho Tire Co. v. Carmichael.[31]  In that case, the Supreme Court determined that the trial court’s gatekeeping function involving relevance and reliability extended to all expert testimony, whether scientific or not.




            Although there exist numerous appellate court decisions which arguably misinterpret Robinson and Havner, it is clear that the trial court’s gatekeeping function will present a critical focus of trial court litigation in the future.  In Texas, the trial judge is afforded great discretion in discharging his or her duty as the gatekeeper of evidence.  The Texas high court, however, has positioned itself to review decisions to admit or exclude expert testimony on a de novo basis.  This judicial approach should bode well for defendants currently involved in Texas litigation. At best, specific case law now exists to challenge so-called experts whose opinions evolve from a flawed methodology before their testimony impacts the jury. At worst, the defense can determine at a relatively early stage exactly what claims the plaintiffs’ expert will support.  And, if not supported by an “expert,” the defense can subject those claims to a motion for summary judgment.



[1]           509 U.S. 579 (1993).

[2]           (1) The testability of the theory; (2) whether the theory or technique has been subjected to peer review and publication; (3) the potential rate of error and (4) the general acceptance of the theory or technique in the scientific community. Id. at 593, 594.

[3]           923 S.W.2d 549 (Tex. 1995).

[4]           Id. at 557.

[5]           924 S.W.2d 148 (Tex. 1996).

[6]           Id. at 153 (emphasis added).

[7]           Id. at 154.

[8]           938 S.W.2d 29 (Tex. 1997).

[9]           See id. at 30.

[10]          Id.

[11]          953 S.W.2d 706 (Tex. 1997).

[12]          Id. at 714.

[13]          Id.

[14]          Id. at 717-18.

[15]          Id. at 718.

[16]          Id.

[17]          Id. at 719.

[18]          Id.

[19]          Id. at 724.

[20]          Id. at 723.

[21]          Id.

[22]          Id.

[23]          Id.

[24]          Id.

[25]          Id. at 724.

[26]          Id. at 720.

[27]          Id.

[28]          971 S.W.2d 402 (Tex. 1998).

[29]          972 S.W.2d 713 (Tex. 1998).

[30]          Id. at 726.

[31]          526 U.S. 137 (1999).


(Authors’ bios)

Jerry C. Parker is a founding and present managing partner in the Houston and Tyler Texas law firm of Sammons & Parker, P.C.  His trial practice concentrates on defending environmental and long-term exposure, product liability and negligence claims.  Accordingly, Mr. Parker is approved panel counsel for a litany of carriers relating to environmental and extra-contractual matters; he also serves as state counsel for products involved in asbestos and silica related matters.  He is a frequent guest speaker regarding the management of large multi-plaintiff/defendant mass tort claims and other related management issues.  Mr. Parker is a member of the Federation of Insurance & Corporate Counsel  and the American Board of Trial Advocates (ABOTA). He is licensed to practice before all Texas state courts, as well as the United States District Court for the Eastern, Southern and Northern District of Texas and the Fifth Circuit Court of Appeals in New Orleans.


Reid Wm. Martin is a partner in the law firm of Sammons & Parker, P.C.  His practice is focused on environmental, nursing home and appellate litigation, as well as insurance coverage questions.  Mr. Martin is licensed to practice before all courts of the State of Texas as well as the Southern, Northern and Eastern United States District Courts of Texas, the Fifth Circuit Court of Appeals, and the Supreme Court of the United States.  He received his undergraduate degree from the University of Texas at Austin and his J.D. degree from South Texas College of Law in Houston.