Dissenting opinion by:
SARAH B. DUNCAN, Justice.I respectfully dissent.
Applicable Law and Standard of Review
To be admissible, expert scientific testimony must be “‘sufficiently reliable and relevant to help the jury in reaching accurate results.’ ” Hartman v. State, 946 S.W.2d 60, 62 (Tex.Crim.App.1997) (emphasis in original) (quoting Kelly v. State, 824 S.W.2d 568, 572 (Tex.Crim.App.1992)). “To be considered reliable, evidence based on a scientific theory must satisfy three criteria: (1) the underlying scientific theory must be valid; (2) the technique applying the theory must be valid; and (3) the technique must have been properly applied on the occasion in question.” Id. The burden of persuasion on these issues rests with the proponent of the evidence, and the standard of proof is by clear and convincing evidence. Kelly, 824 S.W.2d at 573.
On appeal, we review the trial court’s admission of expert scientific testimony under an abuse of discretion standard. Waring v. Wommack, 945 S.W.2d 889, 892 (Tex.App.—Austin 1997, no pet.). Under this standard, we view the evidence in the light most favorable to the trial court’s ruling, affording almost total deference to findings of historical fact supported by the record. Loserth v. State, 963 S.W.2d 770, 772-74 (Tex. Crim. App. 1998); Guzman v. State, 955 S.W.2d 85, 89 (Tex. Crim. App. 1997). However, when the resolution of a factual issue does not turn upon an evaluation of credibility or demeanor, we review the trial court’s determination of the applicable law, as well as its application of the appropriate law to the facts it has found, de novo. Guzman, 955 S.W.2d at 89.
Validity of Underlying Scientific Theory
“In alcohol-related matters, such as driving under the influence, the most common toxicological question is: Given a blood alcohol concentration (BAC) at a specific time, can the BAC at any earlier time be predicted reliably?” Mark J. Reasor & Mark R. Montgomery, Driving Under the Influence: Is Retrograde Extrapolation of Blood Alcohol Scientifically Valid?, 9 W. VA. Law. 14, 14 (1996). The answer is “yes” — a process known as retrograde extrapolation can provide an answer if one knows certain information. See id. The trial court was thus entitled to conclude, as it must have, that the theory underlying McDougal’s testimony — retrograde extrapolation — is a valid scientific theory, and this prong of the Kelly test was met.
Validity of the Technique Applying the Theory
To apply the theory of retrograde extrapolation, one must either (1) know the type of alcohol consumed, the rate of consumption, and various other factors or (2) make assumptions regarding the relevant factors. Id.; see also, e.g., Texas Department of Public Safety, Texas BREath Alcohol Testing Program Operator Manual at 5-10 (TLE/br-38 (Rev.9/96)) (“Unless all *495the variables [food, time, type of alcohol, rate, and time of last drink] are known, the exact ethanol concentration at the time of arrest cannot be accurately and precisely predicted. The alcohol concentration may be higher, lower, or the same.”).
In the past, many assumed a person’s alcohol concentration at the time he was stopped “was at least as high, and probably higher” than later, when an alcohol concentration test was administered. Richard F. Fitzgerald & David N. Hume, The Single Chemical Test for Intoxication: A Challenge to Admissiblity, 66 Mass. L.Rev. 23, 28 (1981); see Jennifer L. Paris-er, Note, In Vino Veritas: The Truth About Blood Alcohol Presumptions in State Drunk Driving Law, 64 N.Y.U. L.Rev. 141, 149-50 (1989). However, today “[m]ost experts agree that it ordinarily takes forty-five to ninety minutes to attain a peak BAC level on an empty stomach, and two to three hours if alcohol is consumed with or after a meal, while a few contend that the time lag between alcohol consumption and' absorption into the blood stream is even longer.” McLean v. Moran, 963 F.2d 1306, 1309-10 (9th Cir.1992); see, e.g., Kurt M. Dubowski, Absorption, Distribution and Elimination of Alcohol: Highway Safety Aspects, Supp. 10 J. Stud, on Alcohol 98, 99 (1985). In short, it is invalid to assume a person’s alcohol concentration either remains the same or increases over a forty minute period. Therefore, if one makes this invalid assumption, his technique of applying the theory of retrograde extrapolation is likewise invalid.
In this case, McDougal testified he did not know Hartman’s weight, drinking history, or food intake. Instead, he based his technique of applying the theory of retrograde extrapolation on an assumption reliable scientific principles holds invalid, that is, Hartman’s alcohol concentration either remained the same or increased between the time he was stopped and the time he submitted breath samples. As a result, McDougal’s technique of applying the theory of retrograde extrapolation is itself invalid. Admitting McDougal’s retrograde extrapolation testimony over Hartman’s objection was thus error.
Harm
The majority holds Hartman cannot show he was harmed by the erroneous admission of McDougal’s testimony because the jury was charged under both definitions of intoxication. I disagree.
During the lengthy pendency of this appeal, the Texas Court of Criminal Appeals promulgated amended rules of procedure, including an amended rule on harmful error. See Tex.R.App. P. 44.2. Under the rules in effect at the time Hartman appealed and when this court issued its original opinion, an error required reversal “unless the appellate court determine[d] beyond a reasonable doubt that the error made no contribution to the conviction or to the punishment.” Tex.R.App. P. 81(b)(2), 60 Tex. B.J. 408, 409 (Tex.Crim.App.1997, repealed 1997). However, under the rules now in' effect a non-constitutional error “must be disregarded” unless it “affect[s] substantial rights.” Tex.R.App. P. 44.2(b). The amended rules apply “except to the extent that in the opinion of the court their application in a particular proceeding then pending would not be feasible or would work injustice, in which case the former procedure may be followed.” Court of Criminal Appeals Final Approval of Revisions to the Texas Rules of Appellate Procedure para. 2 (Aug. 15,1997).
The majority holds Hartman cannot show reversible error under Rule 44.2(b). However, the majority fails to consider whether its application of Rule 44.2(b) is unjust. I would hold it would be unjust to apply the less stringent standard for harmful error contained in Rule 44.2(b) merely because this court erred in failing to apply the Kelly test in its original opinion (which I authored). I would therefore reverse the trial court’s judgment under the standard set forth in repealed Rule *49681(b)(2) and remand this cause to the trial court for a new trial.