law-expert-opinion-testimony | admission exclusion of evidence | evidentiary rulings review on appeal
harmful error analysis rule | property owner rule |


Rule 702 of the Texas Rules of Evidence governs the admissibility of expert testimony. TEX.R. CIV.
EVID. 702; E.I. du Pont de Nemours & Co. v. Robinson, 923 S.W.2d 549, 554 (Tex.1995). Rule 702
provides: "if scientific, technical, or other specialized knowledge will assist the trier of fact to
understand the evidence or to determine a fact in issue, a witness qualified as an expert by
knowledge, skill, experience, training, or education may testify thereto in the form of an opinion or
otherwise." TEX.R. CIV. EVID. 702. The testimony must be relevant and based on a reliable
foundation. Gammill v. Jack Williams Chevrolet, Inc., 972 S.W.2d 713, 727-28 (Tex.1998); Robinson,
923 S.W.2d at 554. Once the opposing party objects to proffered expert testimony, the proponent of
the witness' testimony bears the burden of demonstrating its admissibility. Broders v. Heise, 924 S.W.
2d 148, 152 (Tex. 1996); Robinson, 923 S.W.2d at 557.

If the foundational data underlying an expert's opinion testimony is unreliable, the expert will not be
permitted to base an opinion on that data because any opinion drawn from that data is likewise
unreliable. Merrell Dow Pharm., Inc. v. Havner, 953 S.W.2d 706, 714 (Tex.1997). A flaw in the expert's
reasoning from the data may render reliance unreasonable and render his inferences drawn from
information dubious. Id. In that circumstance, the expert's testimony is unreliable and legally
constitutes no evidence. Id.

TXI Transp. Co. v. Hughes, 306 SW 3d 230 (Tex. 2010)
For an expert's testimony to be admissible, the expert witness must be qualified to testify about
"scientific, technical, or other specialized knowledge," TEX.R. EVID. 702, and the testimony must be
relevant and based upon a reliable foundation. Exxon Pipeline Co. v. Zwahr, 88 S.W.3d 623, 628 (Tex.
2002). An expert's testimony is relevant when it assists the jury in determining an issue or in
understanding other evidence. TEX.R. EVID. 702. But, expert testimony based on an unreliable
foundation or flawed methodology is unreliable and does not satisfy Rule 702's relevancy
requirement. E.I. du Pont de Nemours & Co. v. Robinson, 923 S.W.2d 235*235 549, 556-57 (Tex.
1995) (discussing TEX. R. EVID. 702).
When the reliability of an expert's testimony is challenged, courts "`should ensure that the [expert's]
opinion comports with the applicable professional standards.'" Helena Chem. Co. v. Wilkins, 47 S.W.
3d 486, 499 (Tex.2001) (quoting Gammill v. Jack Williams Chevrolet, Inc., 972 S.W.2d 713, 725-26
(Tex.1998)). To aid in that determination, we have suggested several factors to consider when
assessing the admissibility of expert testimony under Rule 702.[2] We have emphasized, however,
that these factors are non-exclusive, and that they do not fit every scenario. Gammill, 972 S.W.2d at
726. They are particularly difficult to apply in vehicular accident cases involving accident
reconstruction testimony. Ford Motor Co. v. Ledesma, 242 S.W.3d 32, 39 (Tex.2007) (citing Cooper
Tire & Rubber Co. v. Mendez, 204 S.W.3d 797, 802 (Tex.2006)); see also Gammill, 972 S.W.2d at
727. Nevertheless, the court, as gatekeeper, "must determine how the reliability of particular
testimony is to be assessed." Gammill, 972 S.W.2d at 726. Rather than focus entirely on the reliability
of the underlying technique used to generate the challenged opinion, as in Robinson, we have found
it appropriate in cases like this to analyze whether the expert's opinion actually fits the facts of the
case. Volkswagen of Am., Inc. v. Ramirez, 159 S.W.3d 897, 904-05 (Tex.2004). In other words, we
determine whether there are any significant analytical gaps in the expert's opinion that undermine its
reliability. Id.


Whirlpool Corp. v. Camacho, No. 08-0175 (Tex. Dec. 11, 2009)(Johnson)
product liability suit, design defect, laundry dryer fire, expert testimony)(judgment on jury verdict
13th district (13-05-00361-CV, 251 SW3d 88, 01-17-08)  
The Court reverses the court of appeals' judgment and renders judgment.
Justice Phil Johnson delivered the opinion of the Court [in pdf]
(Justice Guzman not sitting)
Electronic Briefs in WHIRLPOOL CORPORATION v. CAMACHO     
An expert’s opinion, to be admissible, must be relevant and reliable. Exxon Pipeline Co. v.
Zwahr, 88 S.W.3d 623, 628 (Tex. 2002). To be relevant, the expert’s opinion must be based
on the facts; to be reliable, the opinion must be based on sound reasoning and methodology.
Id. at 629; Merrell Dow Pharms., Inc. v. Havner, 953 S.W.2d 706, 714 (Tex. 1997). We review
a trial court’s determination that a witness’s testimony is unreliable for an abuse of discretion.
Helena Chem. Co. v. Wilkins, 47 S.W.3d 486, 499 (Tex. 2001). A trial court abuses its
discretion in excluding expert testimony if the testimony is relevant to the issues in the case
and is based on a reliable foundation. Zwahr, 88 S.W.3d at 628; Helena Chem. Co., 47 S.W.
3d at 499.  
State of Texas v. Central Expressway Sign Associates, No. 08-0061 (Tex. Nov. 20, 2009)(Subst. Op.
by O'Neill) (
condemnation, proper method for determining market value, admissibility of expert
testimony, methods to appraise market value of condemned property)
5th district (05 06 00003 CV, 238 SW3d 800, 08 31 07)
motion for rehearing denied    
The Court's opinion of June 26, 2009 is withdrawn and the opinion of this date is issued.
The Court reverses the court of appeals' judgment and remands the case to the trial court.
Justice O'Neill delivered the opinion of the Court.
(Justice Guzman not sitting)  

Also see:
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