In Layton v. State, 280 S.W.3d 235 (Tex. Crim. App. 2009), the issue was the admissibility of the defendant's use of medications without any evidence from which to extrapolate that his use of medications hours before the incident would still have altered his behavior at the time of his arrest. The appellant's arguments were the same in the trial court and in the appellate courts. Layton, 280 S.W.3d at 240. He argued in the trial court that his use of medications was inadmissible without proof of "the accuracy and reliability of the evidence and its relevance" and on appeal argued that the medical evidence was "not reliable, and, therefore, irrelevant." Id. at 240-41. Although unreliable evidence or scientific evidence without a proper foundation may be irrelevant, the converse is not true. Irrelevant evidence is not necessarily unreliable. Thus, when the objecting party contends that evidence is irrelevant because it is unreliable, a reliability objection is necessary to alert the trial court that the three criteria for measuring reliability and the Kelly factors (Kelly v. State, 824 S.W.2d 568 (Tex. Crim. App. 1992)) must now be considered by the court. See Layton, 280 S.W.3d at 241. In that case, the appellant was charged with driving while intoxicated by introduction of alcohol into his system. Id. 237. The trial court allowed in the videotape of the stop, in which appellant admitted to taking both Valium and Xanax the previous day. Id. The appellant objected to admission of the evidence as irrelevant because there was no evidence the drugs, which were taken twenty-four hours and fourteen hours prior to his arrest, would have any effect on his degree of intoxication by alcohol. Therefore, the evidence was irrelevant. Id. at 241. The court of criminal appeals agreed and stated there was no evidence "as to the dosage taken by Appellant, the exact time of ingestion, or the half-life of the drug in the human body." Id. at 242. It further stated that a lay juror is in no position to determine whether the drugs, taken more than twelve hours before the arrest, would have had any effect on intoxication. Id. "There was no testimony indicating that Officer Allen had any medical knowledge regarding the use of Xanax and Valium, or about the effect of combining the medications with alcohol." Id. The Court of Criminal Appeals determined an officer's testimony that a defendant admitted taking the drugs Xanax and Valium was irrelevant because the record contained no evidence that those drugs affected the defendant's level of intoxication. See id. The Layton court held that "a lay juror is not in a position to determine whether Xanax and Valium, taken more than 12 hours before arrest, would have any effect on appellant's intoxication." Id. In Layton v. State, the defendant was convicted of the offense of driving while intoxicated by the introduction of alcohol into the body. Id. at 237. The defendant objected to the admission of evidence pertaining to his use of Xanax and Valium. Id. Specifically, a videotape recording of the defendant's traffic stop showed that the arresting officer had stopped the defendant at approximately 4:00 a.m. because the car that he was driving was protruding into an intersection. Id. The arresting officer asked the defendant if he had taken any medications, and the defendant acknowledged that he had taken both Xanax and Valium pursuant to his doctor's prescriptions for the treatment of his high blood pressure. Id. The defendant then clarified that he had taken Valium at 2:00 p.m. the previous afternoon, but he had not taken any Xanax since the day before the traffic stop. Id. The arresting officer commented that the medications were for "anxiety," not high blood pressure, and he asked the defendant whether he had read the "inserts" included with the medications. Id. The officer further told the defendant that "it probably was not a good idea to be drinking 'on top of those.'" Id. The defendant contended that such evidence "was inadmissible without the State proving the accuracy and reliability of the evidence and its relevance to whether he was intoxicated." Id. at 240. He "noted that without extrapolation on the Xanax and Valium to determine their effect on the body, the State had not shown their relevance to the issue in question." Id. The defendant argued that this evidence should not have been admitted "without expert testimony to provide foundation." Id. at 237-38. The trial court admitted the evidence over the defendant's objection. Id. On appeal, the court of criminal appeals characterized the defendant's challenge as follows: "Appellant's contention on appeal is not that the evidence of his prescription-drug use is irrelevant per se, but that the relevance is conditional upon proof that it is sound and verifiable. Appellant argues that without that showing, the evidence is not reliable, and, therefore, irrelevant." Id. at 241. The court explained that "when the relevance of evidence depends upon the fulfillment of a condition of fact, the court may admit the evidence contingent upon the introduction of evidence sufficient to support a finding of the fulfillment of the condition." Id. (citing Tex. R. Evid. 104(b)). The court further explained that "reliability of scientific evidence demands a certain technical showing and depends on whether the evidence has a basis in sound scientific methodology." Id. (citing Jordan v. State, 928 S.W.2d 550, 555 (Tex. Crim. App. 1996)). The court then set forth, in significant detail, a trial court's obligation in regard to the admission of scientific evidence: Scientific evidence has the ability to mislead a jury that is not properly equipped to judge the probative force of the evidence. Pursuant to Rule 702, it is the responsibility of the trial court to determine whether the scientific evidence offered is sufficiently reliable, as well as relevant, to help the jury in reaching accurate results. This places the trial judge in the role of a "gatekeeper," whose responsibility it is to weed out inadmissible evidence based on a lack of reliability. The proponent of scientific evidence bears the burden of proving to the trial court, by clear and convincing evidence, that the evidence is sufficiently relevant and reliable to assist the jury in determining a fact in issue. We have previously asserted that evidence derived from a scientific theory must meet three criteria in order to be reliable in any given case: "(a) the underlying scientific theory must be valid; (b) the technique applying the theory must be valid; and (c) the technique must have been properly applied on the occasion in question." We also identified an nonexclusive list of factors that could influence a trial court's determination of reliability. These include: (1) the extent to which the theory and procedure are accepted as valid by the relevant scientific community; (2) the technique's potential rate of error; (3) the availability of experts to test and assess the method or technique; (4) the clarity and precision with which the underlying scientific premise and approach can be explained to the court; and (5) the knowledge and experience of the person(s) who applied the methodology on the occasion in question. Id. Applying these principles regarding the admission of scientific evidence, the court noted that, in the case before it, there was no evidence as to the dosage of the medications taken by the defendant, the exact times of ingestion, or the half-life of the drugs in the human body. Id. at 241-42. The court further noted that, in light of the length of time between the ingestion of the medications and the time of the defendant's arrest, lay jurors were "not in a position to determine whether Xanax and Valium, taken more than 12 hours before arrest, would have any effect on the defendant's intoxication." Id. at 242. Finally, the court noted that there was no testimony indicating that the arresting officer had any medical knowledge regarding the uses of Xanax and Valium, or about the effect of combining the medications with alcohol. Id. Thus, the court of criminal appeals held that the trial court had erred in admitting evidence pertaining to the defendant's use of Xanax and Valium "without the State first showing that the evidence was relevant" to intoxication. Id.