OPINION
delivered the opinion of the unanimous Court.
Thе appellant pled guilty to and was convicted of the misdemeanor offense of driving while intoxicated. He was sentenced to 150 days in jail, probated for twelve months, and a fine of $500. On appeal to the Amarillo Court of Appeals, he challenged the trial court’s pre-trial ruling that, had the сase gone to trial, the State would have been permitted to intro
PROCEDURAL POSTURE
A full recitation of the facts of the case is unnecessary to our disposition. 3 The appellant filed several pre-trial motions seeking to ascertain whether the State would be permitted to intrоduce evidence of the breath test results. At a hearing on those motions, it was established that the arresting officer who administered the test, Department of Public Safety (DPS) Trooper Parker, was a certified Intoxilyzer 5000 operator. 4 It was also established that he had little or no understanding of the sciеntific principles behind the machine. The State was able to produce another witness, however, who was a certified technical supervisor for the Intoxilyzer 5000 and was responsible for overseeing the particular Intoxilyzer 5000 that Trooper Parker operated. She was familiar with the sсience and technology upon which it is based and had first-hand knowledge that it was maintained and in good working order on the date Trooper Parker used it to test the appellant. The trial court ruled that the breath test results would be admissible at trial. With that understanding, the appellant later entered a guilty plea, subject to an appeal of the trial court’s pre-trial ruling.
On direct appeal, the appellant argued that the trial court erred. He relied upon a line of cases from this Court, culminating in
Slagle v. State,
in which we purportedly held that the operator of an apparatus for testing аlcohol concentration via a suspect’s breath must be able to demonstrate a working knowledge of the scientific theory behind the particular apparatus before the results of the test will be admissible.
5
The court of appeals rejected this contention, without even citing
Slagle.
Instead, the court of appeals expressly relied upon the first in the same line of cases,
Hill v. State.
6
In
Hill,
we held that, for the results of a breath test to be admissible, the proponent need only demonstrate that the breath test operator and his apparatus must be “under the supervision of one who has аn understanding of the scientific theory of the machine.”
7
The appellant now argues that, by the time
Slagle
was decided, the Court had implicitly overruled
Hill,
and the court of appeals therefore erred to rely on it. We disagree, and find that the
ANALYSIS
Hill versus Slagle
In Hill, we articulated “three essentials to the admissibility of evidence as to the results of [chemical breath] tests[.]” 8 The second “essential” was “[p]roоf that the operator and the machine were under the periodic supervision of one who has an understanding of the scientific theory of the machine.” 9 The appellant makes no argument that the testimony of the supervisor in this case would not have satisfied this essential.
In subsequent cases, the Hill articulation of the second essential was reworded, beginning with French v. State. 10 There, the Court paraphrased the second Hill essential: “the State must show ... (2) the existence of periodic supervision over the machine and operation by one who understands the scientific theory of the machine!.]” 11 This reworking of the language could reasonably be read to require that the аctual “operation” of the test be performed by “one who understands the scientific theory” involved. But that is by no means a necessary interpretation of the French paraphrase, 12 and in the context of the case it is clear that the Court did not intend to change the Hill standard. The Court meant only to reiterate the requirement that both the operator and machine be under the supervision of one who understands the scientific principles involved. There was no intent in French to hold that the operator must necessarily have such knowledge. 13 Unfortunately, the language of the Court’s paraphrase injected an ambiguity, and it is this ambiguity that the appellant attempts to exploit in this case.
Our ambiguous paraphrase of
Hill’s
second essential was carried over into a number of later opinions.
14
None of those cases involved an alleged failure of proof as to the scientific knowledge of the
operator
of the testing apparatus, howеver, and thus, none supports the proposition that this Court has ever unambiguously held that the
operator
of an apparatus for test-
In Harrell v. State, we held that the second Hill essential applies to determine the admissibility of intoxilyzer evidence. 17 In articulating that second essential, we once more carried forward the ambiguity that originated with French. 18 But we neither adopted the erroneous articulation of the Slagle footnote, nor intended to adopt any deviation from the predicate for admissibility we expressly found to have been “enumerated” in Hill. 19 We hold that the law is, always has been, and will remain the same, viz: it is not a part of the predicate for the admissibility of breath test results, including Intoxilyzer 5000 results, that the operator of the aрparatus himself understand the scientific and technological principles behind the apparatus, so long as he is properly certified under the statute to operate it. 20
The Kelly Criteria
Furthermore, the Texas Rules of Evidence have not changed the law in this regard. In
Hartman v. State,
21
a case specifically involving a challenge to the admissibility of intoxilyzer results, we held that the standard for admissibility of scien-
We reject this contention. In the context оf breath test results, the Legislature has already determined that the underlying science is valid, and that the technique applying it is valid as long as it is administered by individuals certified by, and using methods approved by the rules of, DPS. 26 The fact of certification is sufficient to meet the Kelly criteria with respect to the competence of the breath test operator. That the opponent of the evidence can demonstrate that the operator has not retained all of the knowledge that was required of him for certification is a circumstance that goes to the weight, not the admissibility, of the breath test results.
Harmonizing the Transportation Code and Rule 702, we hold that, when evidence of alcohol concentration as shown by the results of analysis of breath specimens taken at the request or order of a peace officer is offered in the trial of a DWI offense, (1) the underlying scientific theory has been determined by the legisla
In a Kelly hearing, then, at which the results of a breath test are challenged, all the trial court need do to satisfy its “gate-keeping” function is to determine whether the technique was properly applied in accordance with the rules of DPS on the particular occasion in question. A peace officer such as Trooper Parker, who is certified by the DPS to operate the Intoxi-lyzer 5000, need not also be able to articulate the scientific principle behind the apparatus or the technology implementing it in order to satisfy the Kelly criteria. As long as the operator knows the protocol involved in administering the test and can testify that he followed it on the occasion in question, he need not also demonstrate any personal familiarity with the underlying science and technology. In short, nothing in Rule 702 or in Kelly calls for an amendment of the second Hill essential, as it is properly understood and articulated. It is not a prerequisite to the admission of the breath test results that the operator himself understand the science and technology involved. 27
CONCLUSION
The judgment of the court of appeals is affirmed.
Notes
.
Reynolds v. State,
. See TexR.App.Proc. Rule 66.3(c).
.
See
. See Tex. Transp. Code § 724.016(a) ("A breath specimen taken at the request or order of a peace officer must be taken and analyzed under rules of the [DPS] by an individual possessing a certificate issued by the department certifying that the individual is qualified to perform the analysis.”).
.
Slagle
v.
State,
.
.
.
.
Ibid. See also, Fluitt v. State,
.
. Id. at 719.
. The ambiguity of this sentence lies in determining whether the prepositional phrase "by one who understands the scientific theory of the machine” should be understood to modify the noun "supervision,” or the noun "operation.” Both readings are awkward, but either is permissible. But to read the prepositional phrase to modify "supervision” accurately paraphrases what the Court held in Hill, while reading it to modify "operation” obviously changes Hill’s seсond essential. Aside from the ambiguity itself, nothing in French indicates that we intended such a change.
. Indeed, while the Court did find a violation of the second Hill essential in French, the violation it identified was a failure to prove that there was a supervisor who "periodically inspected or exercised supervision over the machine used to administer the test.” Ibid. The Court found no failure of proof with respect to the operator of the machine.
.
E.g., Reyna v. State,
.
. In
Young v. State,
.
. That is to say, we held that part of the predicate for admitting the results of an intox-ilyzer test was proof of "the existence of periоdic supervision over the machine and operation by one who understands scientific theory of the machine[.]” Ibid. We expressly identified this in Harrell as the Hill test for admissibility. Thus, as in French, it is apparent that the ambiguity was unintentional and not meant to signal any requirement, not found in Hill itself, that the operator of the intoxilyzer must have knowledge and understanding of the scientific principles by which the intoxi-lyzer detects blood-alcohol concentration.
.
. See note 4, ante.
.
. See former TexR. Cr. Evid. Rule 702; now TexR. Evid. 702.
.
. Id. at 573.
. 37 Texas Administrative Code § 19.7(b) designates "the following hours and areas of instruction” in any program for operator certification for breath alcohol testing:
(1) three hours of instruction on the effects of alcohol on the human body;
(2) three hours of instruction on the operational principles of the breath alcohol testing instrument to be used. This instruction shall include:
(A) a functional description of the testing method; and
(B) a detailed operational description of the method with demonstrations;
(3) fives hours of instruction on Texas legal aspects of breath alcohol testing;
(4) three hours of instruction on supplemental information which is to include nomenclature appropriate to the field of breath alcohol testing;
(5) 10 hours of participation in a laboratory setting operating the breath testing equipment.
. Tex. Transp. Code § 724.064 ("On the trial of a criminal proceeding arising out of an offense under Chapter 49, Penal Code, involving the operation of a motor vehicle or a watercraft, or an offense under Section 106.041, Alcoholic Beverage Code, evidence of the alcohol concentration or presence of a controlled substance, drug, dangerous drug, or other substance as shown by an analysis of a specimen of the person’s blood, breath, urine or any other bodily substance taken at the request or order of a peace officer is admissible.”);
see also Stevenson v. State,
. The appellant does not contend that the State failed to show that the supervisor in this case had an inadequate understanding of the relevant science and technology, nor does he challenge any other aspect of the State’s predicate under Kelly.
