US Pharm
. 2013;38(6):57-60.

Can an individual be convicted of driving under the influence (DUI) or while intoxicated (DWI) while taking prescription medicine as directed by the prescriber? Not under the specific facts presented in a recent decision from the Supreme Court of Iowa.1

Facts of the Case

On August 27, 2010, while on routine patrol, a Des Moines police officer observed the defendant speeding and driving a vehicle in an erratic manner. The vehicle made a few lane changes without using a turn signal. Further, the vehicle was following another vehicle by a distance of only one car length in a 35-mph zone. The officer decided to make a traffic stop. He observed that the defendant had bloodshot, watery eyes and a “deep raspy voice.” When the defendant exited the vehicle, he had “improper balance” and “slow” movements. According to the officer, the defendant was not acting “normal.”

During the traffic stop, the officer asked the defendant to submit to a horizontal gaze nystagmus (HGN) test. (This test involves determining whether the eyes jerk involuntarily when a stimulus moves from side to side). The defendant’s eyes tracked smoothly. The officer also asked the defendant to perform a Romberg’s test. (This test asks a person to tip his head back and estimate the moment when 30 seconds has elapsed). During the test, the officer observed the defendant “swaying back and forth.” The defendant estimated that 30 seconds had elapsed when only 22 seconds had actually passed. The officer also obtained consent for a preliminary breath test, which did not indicate the presence of alcohol. Nevertheless, the officer decided to take the defendant to the police station for further examination.

Before leaving, the defendant asked the officer to retrieve his wallet and cell phone from the car. While the officer looked for these items, he found an orange syringe between the seat and the center console. The officer also discovered an unmarked pill bottle in the defendant’s front pocket when he patted him down. The officer checked the pills against his “drug bible,” a book he kept in his police vehicle that contained descriptions of various drugs. Using this resource, the officer identified the pills found in the unmarked pill bottle as methadone and hydromorphone. The defendant also told the officer that he had taken a hydromorphone tablet at 8 or 9 PM that evening.

At the police station, the officer examined the defendant for physical signs of drug use. He again observed “droopy eyelids, bloodshot, watery eyes” and pupils that were “a little constricted.” The man’s pulse was a “little high” at 100 bpm.

The officer examined the defendant’s eye function. He again administered the HGN test, which was negative. He also performed the “lack of convergence” test, during which the examiner makes two circles in front of the subject’s nose with a finger and then touches the tip of the nose to determine if the person’s eyes converge. The defendant’s eyes did not converge. (Some people cannot converge their eyes even when sober, which is known as convergence insufficiency). However, the officer observed eye tremors and front-to-back swaying while administering the test. The officer then asked the defendant to perform a “walk-and-turn” test. The officer also conducted a finger-to-nose test, during which the defendant was asked to touch the tip of his nose. The defendant missed the tip of his nose four times out of six attempts. The officer concluded the defendant’s coordination was off. The officer did not ask the defendant to perform a one-leg stand test in light of the defendant’s assertion that his back injuries made it problematic for him to do so. During these procedures, the officer concluded that the defendant demonstrated three of eight criteria showing the influence of a drug.

The officer next examined the defendant’s arms and hands for injection sites. He saw bruising over the veins of both arms and red marks that resembled track marks. Because of the lack of pus oozing from the sites, the officer concluded the injections did not occur “within the last few hours,” but instead occurred “within a day or two.” The officer knew that hydromorphone and methadone can be injected.

The officer had received 3 weeks’ training as a drug recognition expert. In addition to his ordinary police work, he had taught drug recognition courses at the Iowa Law Enforcement Academy for the past 2 years.

Based on “the totality of circumstances,” the officer believed the defendant was under the influence of a narcotic. The defendant consented to providing a urine sample for chemical testing. His urine tested positive for methadone.

During the investigation at the police station, the defendant told the officer he was under the care of a physician for pain management and had prescriptions for methadone and hydromorphone. The defendant also said that he had taken both drugs earlier that day.

During the trial, the defendant’s physician, Daniel Baldi, MD, was called as a witness The record shows that since the early 2000s, Dr. Baldi has treated the defendant for chronic back pain following back surgery. For a couple of years prior to the defendant’s arrest, Dr. Baldi had prescribed methadone and hydro-morphone for the defendant for pain management. He testified that methadone has a long half-life and provides long-term relief while hydromorphone is taken for breakthrough pain. Dr. Baldi did not specifically have a discussion with the defendant concerning driving while using the medication and did not advise the defendant to refrain from driving while taking the drugs. Dr. Baldi administered random drug tests on the defendant. The defendant never tested positive for any drug other than those prescribed. Dr. Baldi testified he could not recall any occasion where the defendant ran out of his prescription too soon and noted that it had not been a recent problem for the defendant. He stated that he saw no abuse of the drug by the defendant and that if he had, he would have taken appropriate steps such as seeing him more frequently, taking him off the drug, giving him less medication, providing additional drug screenings, or ending the doctor-patient relationship in the event of illegal abuse.

On cross-examination, Dr. Baldi was presented several pages of monographs for methadone and hydromorphone that accompany a prescription obtained from a pharmacy. The monographs for both methadone and hydromor-phone state: “This drug may make you dizzy or drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activity safely.”

Dr. Baldi stated that both meth-adone and hydromorphone are addictive. He further testified that he had not prescribed the drugs for injection and that he would have been concerned if he had observed the defendant with somnolence or dizziness. He testified that he would be surprised if the defendant was driving erratically, that he had driven beside him coming home from work without observing any problems, and that hundreds of persons receive methadone shots each morning at two local clinics and subsequently drive to work. He further testified that while constricted pupils are a common side effect of all opioids, to the best of his knowledge, nystagmus, or the jerking of the eye, is not.

Trial Court Proceedings

The state charged the defendant with operating a vehicle while intoxicated. The statute provides that a driver commits this offense when driving “[w]hile any amount of a controlled substance is present in the person, as measured in the person’s blood or urine.”2 The defendant pled not guilty, and the case proceeded to trial. At the close of evidence, the defendant moved for a judgment of acquittal based on the prescription defense,3 arguing it was clear that the drug found in the defendant’s urine was consistent with his prescription for methadone and that the state had failed to prove beyond a reasonable doubt that he was not taking it in accordance with the instructions of his physician or in accordance with the labeling instructions of the pharmacy. The court denied the motion and the jury found the defendant guilty.

Iowa Supreme Court Ruling

The Opinion of the Supreme Court begins by recognizing that all of the elements of the crime of driving while intoxicated were proven by sufficient evidence as characterized by the positive urine test for methadone. However, the “fighting issue” was whether the defendant was entitled to acquittal as a matter of law based on the evidence presented relating to the prescription defense.4 The Court noted that it was undisputed that the defendant had a valid prescription for methadone at the time of his arrest. Thus, the real question became: Was there substantial evidence to support the jury’s conclusion that at the time of his arrest the defendant was not taking methadone according to his physician’s instructions and the labeling directions of the pharmacy?

The defendant contended that once a valid prescription is estab-lished, the state must then show that the defendant did not take the prescription as directed by his physician or pharmacy. According to the defendant, the state proved only methadone use, not methadone abuse.

The prosecutor responded that there was substantial evidence to prove intoxication based on the behavior and symptoms exhibited by the defendant during the traffic stop and while the investigation proceeded at the police station. The Court stated that the problem with this theory is that the behavior and symptoms exhibited by the defendant on the day of his arrest were comparatively mild. “Without expert testimony, the evidence is not sufficiently strong to allow a reasonable jury to conclude beyond a reasonable doubt that [the defendant] was abusing rather than simply using methadone according to his prescription.”5,6 The problem, according to this Court, was that “[w]hile the state established that methadone was in the defendant’s urine, it did not introduce any evidence regarding the amount of methadone in his urine. The mere presence of methadone does not establish misuse because its presence could have been the product of valid use consistent with his prescription. Similarly, the mere facts that [the defendant] changed lanes multiple times or sped from one pack of cars to another do not establish misuse.”1

The prosecutor also argued that there was substantial evidence to prove intoxication based on the warnings found in the pharmacy’s labeling instructions. The prosecutor argued that the defendant violated the instruction in the monograph that he should not drive until he was sure he could do so safely. Accordingly, the defendant’s behavior and symptoms demonstrated that he objectively could not drive safely.

The Court responded that while the record shows that the defendant was driving in a less than optimum manner and in a fashion that would to some extent increase the risk of harm to himself and others, many people drive in this fashion without being under the influence of methadone or any other drug. “We do not think there is sufficient evidence in this record for a jury to conclude beyond a reasonable doubt that [the defendant] was not sure he could perform the activity of driving safely as a result of methadone usage when he drove on the night in question. There is no evidence that [the defendant] had been warned in the past that he should not drive because of the side effects of methadone. There is no evidence in the record of previous mishaps or problems that might have put [him] on notice that he should not be driving while taking methadone.”1


While there were three judges who dissented, the majority opinion concluded that there was insufficient evidence for a jury to determine beyond a reasonable doubt that the state disproved the defendant’s prescription medication defense
to operating while intoxicated. Accordingly, the trial court findings were reversed and the defendant was released from custody.


The prescription defense is intended to shield individuals from prosecu-tion for possessing a controlled substance in accordance with their prescriber’s instructions and the warnings provided to a patient by the pharmacy when a proper and legitimate prescription is filled and dispensed. The basic law is that it is unlawful for anyone to possess a controlled substance unless he or she has legal authorization to do so. This is the basis for the defense. One who has the legal authorization to possess a controlled substance should be immune from prosecution for simple possession. This case takes the defense one step further and applies it to the use of a controlled substance while driving a motor vehicle.

While there was no question that the defendant in this case was driving in a somewhat erratic manner and that the police officer was justified in stopping and arresting him, the Court was unwilling to uphold his prosecution in light of the evidence that he was using the medication under a physician’s care. This might be a justifiable decision based on a technical reading of the law, but is the result reasonable in light of the fact that the defendant was driving his vehicle in a manner that could be dangerous to himself or others? Are possession and use of a controlled substance so intertwined that they cannot be separated? Or are there some uses, like driving a vehicle in an erratic manner, that should be reserved for conviction? These are questions pharmacists should address whenever dispensing medications that could be dangerous when used under certain conditions.


1. Iowa v Schories (Slip Op No 11-0719, February 22, 2013), 2013 Iowa Sup Lexis 15.
2. Iowa Code §321J.2(1)(c).

3. Vivian JC. The prescription defense. US Pharm. 2011;36(5):49-51. Accessed April 22, 2013.
4. Iowa Code §321J.2(7)(b).
5. State v Lawson, 99 Conn App 233, 913 A2d 494, 504–05 (2007). Holding that expert testimony is required to link a trace amount of methadone to a driving impairment.
6. State v Bealor, 187 NJ 574, 902 A2d 226, 237-38 (2006). Noting that expert testimony is preferred on a cause of intoxication other than alcohol.

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