Mansfield, J., delivered the opinion of the Court which McCormick, P.J., Meyers, Holland, and Womack, JJ., join. Price, J., filed a concurring and dissenting opinion. Baird and Overstreet, JJ., dissent. Keller, J., dissents and filed a separate opinion.

These cases present two questions: (1) whether the Fourth Court of Appeals erred in holding that it is a defense to prosecution under Texas Health and Safety Code § 481.117(a) for possession of a controlled substance that the substance was obtained pursuant to a valid foreign prescription and brought into this country in accordance with federal law, and (2) whether the Fourth Court of Appeals erred in holding that the record evidence “establishe[d]” that defense.

On December 11, 1995, a Frio County grand jury returned two indictments in the 218^th District Court charging appellant with possession of controlled substances. One of the indictments charged her with possession of 28 grams or more but less than 200 grams of diethylpropion; the other charged her with possession of 28 grams or more but less than 200 grams of diazepam. See Tex. Health & Safety Code § 481.117(a) & (c). The cases were consolidated and tried before a jury on August 12, 1996.

Only three witnesses testified at trial. The State’s witnesses, Frio County Sheriff Carl H. Burris and Department of Public Safety Criminalist Juan B. Ortiz, III, testified in relevant part as follows: Sometime on October 28, 1995, Sheriff Burris, while patrolling Interstate Highway 35 in Frio County, observed a vehicle traveling north at excessive speed. Burris pursued and stopped the speeding vehicle and issued a citation to the driver. Burris also asked the driver where he and his passenger, appellant, had been that day. The driver responded that they had been in Mexico, shopping. Burris then asked the driver what they had purchased, and the driver responded that they had purchased prescription drugs. Appellant showed Burris the drugs in question--five small boxes of Tenuate® tablets (diethylpropion) and two small boxes of Valium® tablets (diazepam)--together with a copy of a prescription for the drugs.¹ Appellant explained to Burris that a Mexican physician had prescribed the drugs for her. Burris examined the prescription, which, although partly in English and partly in Spanish, appeared regular on its face and indicated, among other things, that it was written for appellant. The prescription also indicated that it was written by Dr. Joaquin Izaguirre Quintero, a general practitioner, whose address was stated as J. Ortiz de Dominguez # 2801, Nuevo Laredo, Tamaulipas, Mexico. The prescription was stamped “CLEARED U.S. CUSTOMS LAREDO, TEXAS.”

Appellant took the stand in her defense and testified in relevant part as follows: On the day in question, she and her son traveled across the border to Nuevo Laredo to shop and to buy prescription diet pills, which were much cheaper there than in the United States. Appellant met with a Mexican physician, who prescribed a three-month supply of Tenuate, to help appellant lose weight, and a three-month supply of Valium, to help her sleep at night. Appellant had the dual prescription filled at a Nuevo Laredo pharmacy and then spent some time shopping with her son before crossing the border back into Texas. While at the border, appellant declared all of her purchases to United States Customs Service officials, who had her fill out some forms before permitting her entry into the United States.

At the conclusion of the guilt/innocence stage, the jury found appellant guilty of each offense as charged in the indictments. The jury then assessed appellant’s punishment for each offense at the minimum authorized by law: imprisonment for two years, probated.

On appeal, appellant argued, among other things, that the statute under which she had been convicted, Texas Health and Safety Code § 481.117(a), was void for vagueness. See Fogo v. State, 830 S.W.2d 592, 595 (Tex.Crim.App. 1992). The Fourth Court of Appeals rejected that argument, however. Wright v. State, 955 S.W.2d 393, 394-395 (Tex.App.--San Antonio 1997). The Court of Appeals did not address directly any of appellant’s other arguments, but it did address, apparently as unassigned error,² the question of whether it is a defense to prosecution under § 481.117(a) for possession of a controlled substance that the substance was obtained pursuant to a valid foreign prescription and brought into this country in accordance with federal law. After a lengthy analysis, the court, in effect, held that the answer was yes. Id. at 396. The court then addressed the evidence in this case:

The record in the instant case establishes that Wright was engaged in lawful conduct. She travelled to Nuevo Laredo, Mexico to visit Dr. Ortiz De Dominguez [sic], a fully-licensed physician. Dr. Dominguez prescribed valium and diethypro pion [sic] to Wright and she filled the prescriptions in Nuevo Laredo, Mexico. At the border, Wright presented her medication and related papers to U.S. Customs officials. She completed paperwork indicating that the medication was for personal use. Wright’s documents were stamped with the notation “Cleared U.S. Customs, Laredo, Texas,” and she was allowed to proceed. The record thus establishes that Wright was in lawful possession of her prescription medication as defined by the [Texas Controlled Substances] Act because her actions were authorized under federal law.

Ibid. Finally, the court reversed the judgments of the trial court and remanded the cases to that court with instructions to dismiss the indictments.

We subsequently granted the State’s petitions for discretionary review to determine whether the Court of Appeals had erred as to either of its holdings. See Tex. R. App. Proc. 66.3(b) & (f).

In its petition and brief to this Court, the State continues to insist that possession of foreign- prescribed controlled substances is always unlawful under § 481.117(a). The State also argues, perforce, that the record evidence does not establish any defense to prosecution and that, therefore, the Court of Appeals erred in remanding the cases to the trial court with instructions to dismiss the indictments.

We turn first to the question of whether it is a defense to prosecution under § 481.117(a) that the controlled substance was obtained pursuant to a valid foreign prescription and brought into this country in accordance with federal law. We agree with the Court of Appeals that the answer to that question is yes, but our analysis takes a different route.

Section 481.117(a) provides: “Except as authorized by this chapter [that is, Chapter 481 of the Texas Health and Safety Code, which comprises the Texas Controlled Substances Act], a person commits an offense if the person knowingly or intentionally possesses a controlled substance listed in Penalty Group 3,^[3] unless the person obtains the substance directly from or under a valid prescription or order of a practitioner acting in the course of professional practice.” Section 481.002(39) defines “practitioner,” in relevant part, as a Texas physician or a physician registered with the Federal Drug Enforcement Administration, so the third clause of § 481.117(a) does not authorize the possession of foreign-prescribed controlled substances. However, the first clause of § 481.117(a), “Except as provided by this chapter,” indicates that other provisions of the Texas Controlled Substances Act must be examined in order to define accurately the possession offense and the defenses thereto.

Of relevance here is § 481.062, titled “Exemptions,” which provides in subsection (a)(3) that an “ultimate user” “may [lawfully] possess a controlled substance under this chapter.”⁴ Section 481.002(48) defines “ultimate user,” in relevant part, as “a person who has lawfully obtained and possesses a controlled substance for the person’s own use.” And § 481.002(24) defines “lawful possession” as “the possession of a controlled substance that has been obtained in accordance with state or federal law.” (Emphasis added.)

A person claiming the benefit of the “ultimate user” exemption or defense has the burden of producing evidence that raises that defense. Tex. Health & Safety Code § 481.184(a). Once the defense is raised, the trial court must, if requested, instruct the jury that a reasonable doubt on the issue requires that the defendant be acquitted. Tex. Penal Code § 2.03(c)-(e).

Turning to the relevant federal law, we find that the Federal Comprehensive Drug Abuse Prevention and Control Act of 1970 provides that a person may lawfully possess a controlled substance⁵ if the substance “was obtained directly, or pursuant to a valid prescription or order, from a practitioner, while acting in the course of his professional practice.” 21 U.S.C. § 844. The Federal Act defines “practitioner” to include “a physician ... licensed, registered, or otherwise permitted, by the United States or the jurisdiction in which he practices ... to ... dispense ... a controlled substance in the course of his professional practice.” 21 U.S.C. § 802(21) (emphasis added). The Federal Act prohibits the importation of controlled substances but provides that the United States Attorney General may, by regulation, exempt from that prohibition a person who has lawfully obtained a controlled substance for personal medical use. 21 U.S.C. §§ 952-956. The Attorney General, acting through the Drug Enforcement Administration, has promulgated such a regulation, 21 C.F.R. § 1301.26, which provides:

Any individual who has in his/her possession a controlled substance ... which he/she has lawfully obtained for his/her personal medical use ... may enter ... the United States with such substance ..., providing the following conditions are met:
(a) The controlled substance is in the original container in which it was dispensed to the individual; and
(b) The individual makes a declaration to an appropriate official of the U.S. Customs Service stating:
(1) That the controlled substance is possessed for his/her personal use, or for an animal accompanying him/her; and
(2) The trade or chemical name and the symbol designating the schedule of the controlled substance if it appears on the container label, or, if such name does not appear on the label, the name and address of the pharmacy or practitioner who dispensed the substance and the prescription number, if any; and
(c) The importation of the controlled substance for personal medical use is authorized or permitted under other Federal laws and state law.

In summary, it is a defense to prosecution under Texas Health and Safety Code § 481.117(a) for possession of a controlled substance that (1) the substance was obtained abroad for personal medical use directly from, or pursuant to a valid prescription from, a physician permitted in his jurisdiction to dispense controlled substances and (2) the substance was brought into the United States in accordance with 21 C.F.R. § 1301.26.⁶

We turn now to the Court of Appeals’ second holding. As noted previously, the Court of Appeals held that the evidence “establishe[d]” that Wright’s conduct was lawful. In making that determination, the Court of Appeals took on the role of fact-finder, which it may not do. Clewis v. State, 922 S.W.2d 126, 135 (Tex.Crim.App. 1996). The role of fact-finder is reserved for the jury. Tex. Code Crim. Proc. art. 36.13. The jury in this case was not instructed on the “ultimate user” defense or any other defense, and it was error for the Court of Appeals to find that the defense was proven conclusively.

Accordingly, we vacate the judgment of the Court of Appeals and remand the case to that court for consideration of appellant’s remaining points of error.

DELIVERED DECEMBER 9, 1998

¹ We take judicial notice that Tenuate is an appetite suppressant and Valium is a tranquilizer. See D. Sifton (ed.), et al., The PDR Family Guide to Prescription Drugs, pp. 569 & 616 (5^th ed. 1997).
² An appellate court may, in its discretion, consider unassigned error. Whatley v. State, 946 S.W.2d 73, 76 n. 6 (Tex.Crim.App. 1997).
³ Penalty Group 3 includes diethylpropion and diazepam. See Tex. Health & Safety Code § 481.104.
⁴ An “ultimate user” exemption exists, apparently, in every state and federal controlled substance statute. See D. Bernheim, Defense of Narcotics Cases § 1.11 (1990).
⁵ We need not discuss which substances are controlled under federal law, except to note that diethylpropion and diazepam are. See 21 C.F.R. § 1308.14.
⁶ We express no opinion as to whether the evidence at appellant’s trial raised the “ultimate user” defense or whether the trial court should have instructed the jury on it. Those are questions the Court of Appeals may need to address as it considers appellant’s remaining points of error.