If recreational marijuana finally becomes legal in Illinois, driving to a cannabis dispensary will be as commonplace as swinging by the liquor store. But are Illinois police officers ready to keep the streets safe from a potential influx of stoned drivers? And can police even tell when a driver is stoned?
Since Colorado began its legalization process in 2012, the number of drivers who tested positive for marijuana involved in fatal accidents has risen dramatically, the Denver Post reported.
Unlike alcohol, there is no definitive test like a Breathalyzer that can indicate whether someone is driving under the influence of marijuana or other drugs. In place of a such a test, the state has started training cops in a monthlong program called the International Drug Evaluation and Classification Program. About 50 Illinois officers a year have become certified “drug recognition experts,” better known as “DRE officers,” according to Thomas Turek, the DRE Illinois State Coordinator for the International Association of Chiefs of Police.
DRE officers not only determine drug impairment, but attempt to classify the type of drug the person took into one of seven categories using a 12-step evaluation. Although drugs affect users differently, DRE officers are supposed to be able to identify someone under the influence of pot or other substances by taking a pulse and examining eye movements, among other tests.
The screening process can also include a toxicology exam involving a blood or urine test. A urine test is problematic, because the screening doesn’t return definitive results saying whether the person tested was under the influence of a specific drug at the time the test was taken, experts said.
“A urine drug screening won’t tell you about what’s in front of you, it’ll tell you metabolite [levels],” says Dr. Henry Swoboda, a medical toxicology specialist at Rush University Medical Center.
Metabolites are not the actual drug. They’re produced after substances are processed through the body and turned into urine. Testing positive for marijuana metabolites, for example, does not prove someone was impaired while he or she was behind the wheel. In fact, according to Swoboda, a driver could have smoked weed days before the test was taken and might not have been impaired while driving—but still test positive for the drug.
Though they yield more reliable results, blood tests are harder to administer than urine tests because only a licensed medical practitioner, such as a registered nurse, phlebotomist or doctor, can collect samples under Illinois Compiled Statutes.
DRE officers are not legally needed to convict someone of driving under the influence of drugs, but there also is no penalty for refusing to be evaluated by a DRE officer. Illinois drivers do, however, have to submit to a blood or urine test in the case of someone suspected of driving under the influence of drugs or alcohol.
Still, the officers do play a role in court. “A DRE can easily be qualified, by a judge, as an expert witness in court,” says Sergeant Justin Luria, a Lincolnwood DRE officer, allowing the officer to testify as to whether he believed the driver was high or not.
Officers who don’t have the drug training can face challenges in court, attorneys said.
“If they give me a case where the officer is not a DRE, and he’s trying to imply that my client was under the influence of drugs, I have a field day with that officer,” says Chicago defense attorney Adam Shepard. “It’s very important for the defendant’s rights that the state use a DRE.”
But Shepard cautions that DRE officers aren’t really experts, either. “When these DREs start to talk about the science of drugs, they could get tripped up,” he warns. “They’re not pharmacologists, they’re not scientists, they’re not doctors. They’re police officers that are trained in what symptoms indicate what drug was used.”
The ACLU in Georgia has filed a lawsuit against police in Cobb County,  near Atlanta, saying the DRE program is unreliable. The case revolves around three people who were arrested by a DRE officer for driving under the influence of pot—only to later be found clear of the drugs through blood tests.
Experts said a blood or a urine test and a DRE evaluation are the best way to determine intoxication at the time of arrest. But many police departments do not have the resources to conduct both tests and have few trained officers. Chicago, for example, only has only one DRE officer on its entire force.
“It’s hard for anything in a single test to fully describe a complex situation,” Swoboda says. “DRE officers are only pieces of that puzzle.”