Just in time for St. Patrick’s Day, San Diego Police Department officers began swabbing drivers’ cheeks to look for evidence of marijuana and other impairing drugs.

In March 2017, the San Diego Police Foundation donated two Dräger DrugTest 5000 machines to the department. Each machine is about the size of a bookshelf stereo system, and after an officer obtains a saliva sample, the gadget can determine if the sample contains any opiates, methamphetamine, amphetamine, marijuana, cocaine, methadone or benzodiazepines (the main ingredient in Diazepam, Lorazepam, Valium, Xanax, and other prescription tranquilizers). Then, to determine if the driver was impaired, police must extract a blood sample from the driver. At an earlier news conference, Police Chief Shelley Zimmerman said her department was concerned that Proposition 64, which legalized marijuana in some instances, would increase the number of drug-impaired drivers, and the percentage had already risen significantly in recent years. Chief Zimmerman said that, for now, officers would only use the Dräger DrugTest 5000 at checkpoints.

If the driver refuses to provide a saliva sample, officers will probably arrest the driver based on circumstantial evidence, assuming they believe the driver to be impaired.

DUI Drug Law in California

Proposition 64 did not “legalize” marijuana for all purposes, because it is still a drug under California law. So, driving while high violates Vehicle Code 23152(f), which states that it is illegal for any person to drive any vehicle while under the influence of any drug.

“Any” means “any.” That includes recreational-use marijuana, a prescription benzodiazepine, and even certain over-the-counter medications. In August 2015, a Fairfield man was arrested for driving under the influence of caffeine. Officers reportedly pulled over a man who was driving erratically, and they found some caffeine-based powder performance enhancers in his car. Prosecutors later dismissed those charges, but only because they felt they did not have enough evidence to prove the case beyond a reasonable doubt.

The caffeine case illustrates the two-pronged nature of DUI drug cases in California. First, prosecutors must prove that the driver had ingested a drug, and the aforementioned saliva swab satisfies this element, at least with regard to the substances that the gadget is designed to detect. Under current law, officers usually do not need search warrants to obtain saliva evidence, because the test is noninvasive and the results normally cannot be saved and used for any other purpose.

Second, prosecutors must prove that the driver was under the influence of that substance. In this context, “under the influence” means that “your physical or mental abilities are impaired to such a degree that you no longer have the ability to drive with the caution characteristic of a sober person of ordinary prudence under the same or similar circumstances.”

There is a preliminary element as well, because the defendant must be “driving” the vehicle. This element is the same in both DUI drug and alcohol cases.

Driving the Car

It may be possible to contest the “driving” element in some cases, because it’s not unusual for a person to be behind the wheel but not “driving” the car in the ordinary sense of the word. Perhaps the driver is parked on the street or idling at a corner waiting for a passenger. Or, perhaps the person is in the car to have a private conversation over the phone or with someone else who is physically present.

Although the weight of authority indicates that all four of the above situations constitute driving, since the defendant has the ability to drive, a number of years ago, a California appeals court ruled that the car must be in motion for the defendant to be “driving” the car. So, especially in the latter two situations where there was no intent to drive, prosecutors may not be able to satisfy this element.

This question sometimes comes up in DUI drug cases because the defendant is parked and sleeping off the effects of a previously-ingested drug.

Nature of Substance

In some states, there is a list of prohibited substances, and if the driver did not ingest something on the list, the driver is not guilty as a matter of law. But in California, there’s that nasty “any” word in the statute, as discussed above.

Under the Influence

Prosecutors must rely on circumstantial evidence to establish this element, and that usually means the field sobriety tests. There are three approved FSTs in California:

• HGN: It may sound odd, but the horizontal gaze nystagmus test (following a point with the eyes without moving the head) is arguably the most reliable and most unreliable FST. If administered properly under controlled circumstances, it is about 80 percent accurate, even though drug impairment is not the only cause of nystagmus. But, the environment at the scene, and even at the stationhouse, is usually not controlled.
• HTT Walk: Conditions also play a significant role in the heel-to-toe walk test, because it is easier to walk heel-to-toe over an actual line (like a parking lot stripe) than an imaginary line, it is easier to walk heel-to-toe over a flat surface than an uneven one, and so on.
• OLS: Officers frequently testify that the defendant “failed” the one leg stand due to technicalities like starting with the wrong foot or holding the foot at a slightly incorrect angle.

In these cases, the prosecutor must also prove that the defendant performed poorly on the FSTs because of the substance, and not because of fatigue, nervousness, or some other reason.