Cannabis DUII: How do police spot stoned drivers?

Share on reddit
Share on facebook
Share on twitter
Share on linkedin
Share on pinterest
Share on email
Share on pocket

Everyone agrees that driving while stoned is a bad thing. After that, however, it’s hard to get a consensus. What constitutes driving while high? What are the legal standards for a marijuana DUII?

And how big of a problem is it?

Chelsea Jones, Jackson County deputy district attorney, says she couldn’t provide that specific data about the number of marijuana DUIIs because “marijuana is lumped in with other controlled-substance driving violations.”

Medford police Sgt. Trevor Arnold, a drug recognition expert, says, “I’ve not personally seen an increase.”

Studies in Colorado and Washington seem to track with Arnold’s experience here. A report cited in TIME magazine by the Colorado State Patrol shows that in the first quarter of 2017, the number of marijuana DUIIs dropped by 33.2 percent from the same period in 2016. Washington state data tallies with the Colorado stats.

Paul Loney, a lawyer and founder of Loney Law Group, which specializes in, among other services, defense in marijuana DUII, says he hasn’t seen “anything new” since legalization.

“It has always been out there,” he says.

These observations about the extent of marijuana-impaired driving — from people involved in DUII enforcement — seem to be good news, but one stoned driver on the road (or in your neighborhood) is one too many. And here is where it gets more complicated for police.

Marijuana DUIIs are problematic for law enforcement, because there is no straight-across test for it like there is with alcohol.

Breathalyzers don’t work for somewhat technical reasons, and urine tests will show a presence of THC in the system, but because THC is stored in fat cells, it can stay in your system much longer than alcohol, so urinalysis won’t say when a driver smoked cannabis or whether he is currently intoxicated.

Some states (six at this point) use a blood-THC test, but this is controversial because there is no agreed-upon, standardized amount that guarantees impairment. It appears that Oregon is not going there.

In a recent DUII legislative report, the Oregon Liquor Control Commission said it is recommending against a per se blood-THC limit.

“Due to restrictions on cannabis research and limited data, it is difficult to make definitive statements about the risk of THC-intoxicated driving,” the report says. “The body of evidence that does exist indicates that while attitudes toward driving after marijuana use are considerably more relaxed than in the case of alcohol, the risk of crashes while driving under the influence of THC is lower than drunk driving. Little evidence exists to compel a significant change in status quo policy or institute a per se intoxication standard for THC.”

In addition to testing complications, there are other issues with marijuana testing and enforcement for drivers. As anyone familiar with cannabis knows, the same amount can affect people very differently. Edibles and smoking can have different effects, while gender, percentage of body fat, and experience of use are also factors.

How Marijuana DUII Enforcement Works in Oregon

With all these chemical tests problematic and inconsistent, Oregon police rely on an old-school method for enforcement: Observation.

Here’s how it works: A policeman might observe a driver behaving erratically, such as making abrupt lane changes, speeding or the perennial driving with headlights off. Then there are other issues that can lead to a traffic stop, such as expired plates or a broken taillight.

The officer will interview the driver and look for clues of intoxication — in the case of marijuana, those could include red eyes, inappropriate laughter, even candy wrappers all over the front seat, says Sgt. Arnold.

“It’s a fact that marijuana use stimulates appetite,” he says. “So it is very common to observe food wrappers and containers in the cars we stop.”

If an officer suspects impairment, he or she will apply a field sobriety test.

If a Breathalyzer test is taken and there is a lack of alcohol or a very low level in the system, but there are still signs of impairment, the observations go to the next level. This is the where the drug recognition expert comes in.

A DRE is a trained impairment observer who has gone through a standardized training program and uses a standardized protocol.

Arnold is a certified DRE instructor and regional coordinator. He says there are 25 DREs in Jackson and Josephine counties.

“When I pull over someone on suspicion of DUII, they always tell me they’ve had two beers,” he says. “When I pull someone over for suspicion of driving under the influence of marijuana, they always say they’ve had just one joint.”

DREs use a 12-step process to examine a DUII suspect, including an interview with the arresting officer, a preliminary examination, an eye examination, vital signs and pulse checks, divided attention tests, dark room evaluations (this checks on pupil size), the suspect’s statements and other tests and observations.

It took many years to come up with a national standard for drunken driving, so it’s only natural that testing, education and standards for marijuana DUIIs will take a number of years to evolve into some sort of standard. This doesn’t factor in the states that don’t yet have legal marijuana.

“The problem I find is that cannabis relaxes your inhibitions and makes you think it’s safe to drive, which is the same thinking as people drinking have,” says Arnold. “I would say that if you’re feeling the effects, don’t drive.”

The best thing you can do is to drive sober, and the problem goes away by itself. If you do feel under the influence, and you must go out, call a taxi, Uber or Lyft, or find a sober friend to drive.

Sometimes it’s better to simply go for a walk, or stay in and watch a movie, or as Loney suggests, read a book.

Jefferson Reeder is a freelance writer living in Medford. Reach him at



Summer 2020 TOC:

  • Cannabis Entrepreneurs: The women behind ‘Ladies of Paradise’
  • Terroir: Inside the science of tasty bud
  • Cannabis Cooking: Canna-balls styled after Alice’s ‘Brownies’
  • Retail: Home delivery gets a boost
  • Profile: River City Retail has a winning formula
  • Retail: Pandemic fuels pot-buying explosion
  • Religion: Cannabis for churchgoers
  • Growing: Hardy Seeds in Ashland shares why hemp loves company
  • COVID-19: Hemp farming – ‘It’s a lot safer than working at McDonalds’
  • Retail: Drive-thru bud at La Mota

SO Famous


Marijuana Trading Cards? Check out this up-and-coming weed entrepreneur from Klamath Falls, OR.

Play Video

Murphy Hemp and Wellness in Grants Pass is serving up an alternative form of medicine. Here they break down some variants in CBD – isolates, broad-spectrum, and full-spectrum (also know as whole plant extract).