Now that medical marijuana has been legal in Ohio for more than a year, the training program that police officers go through to spot drug impairment faces greater scrutiny.

The Ohio Highway Patrol recently recertified eight Ohio police officers, including one from the Columbus Division of Police, as drug-recognition experts after they completed training that is intended to help traffic cops better spot drivers who are intoxicated on illegal drugs or marijuana.

Drug-recognition training is intended to make it harder to get away with impaired driving, and ultimately to reduce traffic deaths through better enforcement.

But the training that officers receive at the patrol’s academy at the state fairgrounds has its critics, who contend that research doesn’t support its methods.

Law enforcement officials, on the other hand, laud the training, saying that drug-recognition expert (DRE) techniques are backed by rigorous study.

Get the news delivered to your inbox: Sign up for our morning, afternoon and evening newsletters

With Ohio having legalized medical marijuana, more than 90,000 residents have medical marijuana cards, and defense attorneys worry that officers will unfairly step up intoxicated-driving arrests because they suspect that more people are using the drug.

“When you’re a hammer, everything looks like a nail,” said Tim Huey, a Columbus criminal-defense attorney.

Sgt. Samuel Criswell, the highway patrol’s DRE coordinator, said law enforcement officers make arrests only when they have solid evidence.

“We deal in absolutes and facts,” he said.

Courts actually saw a decrease in drugged-driving cases in 2019. In Franklin County Municipal Court, for example, cases of driving under the influence of marijuana dropped to 26 in 2019 from 54 in 2018. Prosecutors, however, have the option of citing drivers for a general impaired-driving offense in cases of suspected drug use, making it difficult to draw conclusions from the numbers.

Studies have shown that marijuana makes drivers more likely to cause a crash, said Dr. Melinda Ford, an addiction specialist for OhioHealth Physician Group in Athens. Drivers under the influence of marijuana “are two to seven times more likely to be responsible for a crash compared to a sober driver,” she said.

In most instances, officers who suspect illegal drug or marijuana use give the standard field sobriety test, which is designed to spot drunken drivers.

Studies differ on the effectiveness of those tests in detecting drug use. A 2011 study published in the Journal of Psychopharmacology concluded that standard sobriety tests had a limited ability to detect the use of marijuana.

Officers “will rely on those tests improperly,” Huey said.

However, the findings of a 2013 study published in the journal Traffic Injury Prevention largely supported the use of standard field sobriety tests to detect marijuana use.

Columbus police Sgt. Adam Barton, who conducts traffic stops, said the standard tests work.

“If they are impaired, you would see it,” he said.

But Columbus police still want more suspects to undergo a DRE evaluation, which is more rigorous than standard sobriety tests and provides a better case in court.

“It takes about 45 minutes, and we gather a lot of information,” the patrol’s Criswell said.

DRE training requires 172 hours of instruction.

“It’s almost the equivalent of a college quarter in a few weeks,” patrol spokesman Sgt. Nathan Dennis said.

About 220 law enforcement officers in the state are DRE-certified, including 12 with Columbus police. They’re taught 12 steps, including checking a suspect’s coordination, memory, vital signs and muscle tone, and they compare the results with the indicators for certain drugs.

Officers in the field are equipped with breath tests to measure alcohol impairment, but no such test exists for drugs such as marijuana. Blood tests offer conclusive evidence, and drivers face the prospect of losing their license if they refuse to allow blood to be drawn.

However, defense attorneys and medical professionals have raised doubts about Ohio’s marijuana driving limit, and drivers often refuse blood tests, meaning that arresting officers must rely on physical and behavioral clues.

“We’re testing short-term memory, information processing and cognitive function,” Criswell said.

Officer testimony can be enough to secure an impaired-driving conviction, Huey said, making their training crucial.

Marijuana arrests are particularly complicated because the drug affects everyone differently, and certain physical signs are easy to hide, said Gary Wenk, an Ohio State University psychology professor who studies the effects of drugs.

“Most people will develop red eyes and increased heart rate,” Wenk said. “These symptoms can be easily blocked by taking aspirin or ibuprofen.”

Dennis cites a 1986 National Highway Traffic Safety Administration field evaluation of the Los Angeles Police Department that found that DRE techniques successfully spotted drug impairment 94% of the time, and a 1984 Johns Hopkins University study that found that DRE techniques were 91% accurate.

Defense attorneys, however, cite studies that cast doubt on those methods.

A study published in Traffic Injury Prevention in 2007 concluded that DRE techniques successfully spotted drug impairment only around 75% of the time. The researcher said lab tests and further sobriety tests should be incorporated into the process.

pcooley@dispatch.com

@PatrickACooley