Green Lab Teaches Cops How to Know When a Driver Is Stoned

Green Lab Teaches Cops How to Know When a Driver Is Stoned
Westword Photo Illustration

It’s early evening in a parking lot outside a DoubleTree in northeast Denver. At the north end of the lot is a 1987 Winnebago with seven people inside, gathered around a table covered with cannabis products: a concentrate pen, a dab rig, some bud flower and edibles. Once most of the group has gotten loaded, the seven are going to spend the rest of the night at the hotel, with a bunch of cops.

They’re all volunteers in a “green lab,” part of a training program that Understanding Legal Marijuana LLC puts on for law enforcement officials covering all things related to the cannabis industry, including products, culture and how to look for impairment during a roadside sobriety test. This session is also an opportunity for cops to talk openly with cannabis users in an atmosphere far less stressful than a traffic stop.

Last year, the Colorado State Patrol issued 665 citations to drivers impaired by marijuana — slightly fewer than were issued in 2014. About half of the 2015 citations were for marijuana only; the rest involved marijuana and alcohol or marijuana and another substance. Colorado law specifies that drivers with 5 nanograms of THC per milliliter of blood can be prosecuted for driving under the influence. That law, however, includes the term “permissible inference” — which means that even if a driver’s blood tests over the limit, impairment needs to be proven. That’s why many of those citations — the State Patrol doesn’t have records of how many — do not result in convictions.

There’s good reason for the “permissable inference” provision. The way the body processes THC is fundamentally different from the way it processes alcohol. Alcohol is water-soluble, so measuring booze in the bloodstream is an accurate way of determining the level of booze in the brain. But marijuana is fat-soluble, and while THC can dissipate fairly rapidly from the blood of someone who is an infrequent user, it can also build up in the system of a habitual user. The blood of a person who regularly uses cannabis could test at more than 5 nanograms even when that person is sober (see William Breathe's "THC Blood Test"). This makes it difficult to come up with an “over the limit” level comparable to blood alcohol content (BAC) levels, and so officers must rely on their judgment.

The ULM green-lab training is designed to help law enforcement better understand when a driver is impaired by cannabis — and when that driver is not. “It’s their legal obligation,” says Chris Halsor, founder of ULM. “They’re not supposed to be arresting people who didn’t commit a crime.” Before legalization, possession was the crime. Since legalization, the crime has been driving while impaired — but law enforcement has had to figure out what cannabis impairment actually looks like.

The public’s attitude about marijuana has also changed since legalization, and juries are no longer going to convict a person just because he tests positive for THC in his blood, Halsor notes. Today, jurors ask: Okay, this person used cannabis, but is he really impaired?

“We want people who are engaged in lawful behavior not to be punished for that,” explains Halsor. “We don’t want stereotype or bias to govern arrest decisions. We want impairment to decide whether  somebody goes to jail.”

Chris Halsor is a prosecutor by background. “I’ve done everything from dog off-leash to first-degree murder,” he says. He’s also a Colorado native who has spent most of his life in metro Denver: Halsor grew up in Lakewood and attended the University of Denver’s Sturm College of Law. In 2008, after eight years as a deputy district attorney with the Jefferson County District Attorney’s Office, Halsor moved to the Colorado District Attorneys’ Council, where he became the state’s first Traffic Safety Resource Prosecutor.

A TSRP is a seasoned prosecutor who can provide training and education for other prosecutors and law enforcement officers on traffic-safety issues, with a strong emphasis on impaired driving. As Colorado’s TSRP, Halsor spent the majority of his time dealing with DUIs and trying to improve the quality of investigations and prosecutions, as well as communications between officers and prosecutors.

Soon he had another issue to discuss: In 2009, Colorado’s dispensary scene was booming — and that same year, the U.S. Department of Justice issued the Ogden memo, which advised U.S. attorneys around the country that time, resources and money should not be wasted in states that had legalized medical marijuana. Essentially, the feds were going to turn a blind eye to medical marijuana operations, despite the drug’s federally illegal status. “Somewhere, in some staff meeting, I think I inadvertently raised my hand and said, ‘I’ll take the marijuana issue,’” Halsor recalls.

He started looking at medical marijuana from a DUI perspective, and began thinking seriously about the obstacles that police and district attorneys would face when trying to prosecute stoned drivers, including how to detect impairment and how to convey impairment to a jury. As the Colorado Legislature grappled with marijuana matters, Halsor researched many of them — including the 5 nanogram-limit law, which legislators passed in 2013.

“And I can tell you that, in my mind, it’s of minimal value,” says Halsor. “In addition to the attacks by science, to me its lack of value has more to do with how jurors perceive it than anything else.”

As TSRP, Halsor offered DUI training for officers. The class he taught most often was the comprehensive DUI class, which included wet labs: training sessions where officers could observe drunk people for signs of impairment. Since alcohol is a legal substance, these labs are commonly run by law enforcement agencies, and often friends and family members of officers or dispatch workers volunteer to be the drunks.
Now Halsor wondered about applying the wet-lab concept to cannabis, using the same basic template but having officers interact with people who were high instead of drunk.

But a major obstacle prevented Halsor — or anyone else in government — from creating a green lab. Since marijuana is illegal at the federal level, there was no way that government money was going to pay for it.

Since blood testing is time-consuming and problematic, multiple companies have begun working on portable roadside tests that can show THC levels in saliva. The Colorado State Patrol is currently doing tests with Dräger and Alere, two portable saliva-testing instruments, studying the accuracy of the tests by comparing them to blood tests, in addition to determining how they hold up to things like heat and cold in an officer’s car. But since the Dräger and Alere devices are still being tested, they can’t be used as evidence.
A California company recently announced its creation of a Breathalyzer that can detect both pot and alcohol, but any use by law enforcement is far in the future.

With the lack of a meaningful test or a meaningful number to prove impairment, the process relies on officers being trained to spot the visible and physical signs of driving under the influence. While law enforcement has tried to educate officers on this, marijuana’s federally illegal status and classification as a Schedule 1 substance has made it impossible to study cannabis as thoroughly as alcohol has been.

According to Jen Knudsen, the current TSRP for Colorado, there are many issues when it comes to prosecuting cannabis DUIs, but one of the biggest is education. Everyone involved in a cannabis DUI case, from officers to members of the jury, would benefit from knowing more about the signs and symptoms of impairment. Better-educated law enforcement officers are going to have fewer difficulties explaining cannabis impairment to a jury.

With the start of recreational marijuana sales in Colorado in January 2014, more and more of Halsor’s time was taken up by cannabis: questions about it, requests for him to do presentations. “I was sharing a lot of my knowledge with people in Colorado, but there was a lot of demand from people at institutions in other states that wanted access to what I knew,” he remembers. But he was limited by his government position.

“I always had this [idea] in the back of my head of wanting to do a green lab once I became a private actor,” Halsor says. And in November 2014, he left the Colorado District Attorneys’ Council and founded Understanding Legal Marijuana.

ULM’s first green-lab training was in September 2015. There were a number of challenges that Halsor and his team had to handle before they could hold that initial class — not the least of them location. “I had to deal with the legal issues, and then I also had to deal with the practical and logistical issues,” Halsor remembers. “I needed a place where they would allow for it. I needed a place that wasn’t a dingy warehouse. I needed real accommodations, but also a place that would permit it.”

A place that could provide rooms for out-of-state trainees and was convenient to the airport would be ideal. Obviously, any government facility was off limits, and green labs definitely couldn’t be held at police departments.

The DoubleTree was willing to host Halsor’s first class and house the students, but it wasn’t going to allow volunteers to dose in the hotel. They couldn’t consume cannabis in the parking lot, either: Open public consumption is still illegal in Colorado. “We had to come up with a remedy for that,” says Halsor.

That’s where the RV, which belongs to a friend of his, came into play. Technically, using cannabis inside an RV doesn’t go against the open-container law, since it’s a quasi-residence when it’s parked. In other locations around the state, Halsor would use a party tent.

“When I look back on it, I’m actually impressed that I was able to put this whole thing together,” he says.

At one of his training sessions, South Dakota state trooper Trent Heuertz and Colorado state trooper Nathaniel Grimm (left and center) perform roadside tests on volunteer DJ Morrison.
At one of his training sessions, South Dakota state trooper Trent Heuertz and Colorado state trooper Nathaniel Grimm (left and center) perform roadside tests on volunteer DJ Morrison.
Anthony Camera

Back in the RV, Generationals’ “Ten-Twenty-Ten” is playing on Spotify. There is pizza for the volunteers, along with chips, popcorn and beer (one person will be assigned to consume both cannabis and alcohol). Everyone is crowded in: the seven volunteers, the paramedic who will be on site for the rest of the evening, and Amie Arias, ULM’s green-lab manager.

The volunteers at this lab are a diverse group. There are three women and four men, ranging in age from mid-twenties to fifties; some are regular cannabis users and some just occasional consumers. While they’re encouraged to try different products, they are also allowed to stick with what they are used to.

Anthony Smith, a veteran who’s one of the older members of the group and has some balance problems, is going to be a sober control, so he won’t consume anything tonight. He’s mostly here because his wife, Laura Shroyer, is volunteering. She’s participated in a lab before and liked the experience, both for the educational aspects and the sheer novelty.

Sometimes people volunteer because they think they’re fine to drive when they use, but they wonder how a cop might judge their impairment level. At the green lab, they can find out. Other volunteers sign up for the greater good; they want to help educate police officers. Still others are drawn by the curiosity factor.

“It’s not every day someone will pick you up and feed you dinner and get you high, and then you go talk to cops and go back home,” says Arias. As green-lab manager, one of her responsibilities is stocking the lab with cannabis products. She also monitors the dosing and keeps an eye on the volunteers. Arias has never worked in the cannabis industry; she ended up with this part-time gig because she knew Halsor.

About $200 worth of cannabis products are spread across the table. The products vary from green lab to green lab; this time there’s an Evolab Chroma disposable-oil concentrate pen, a dab rig, a wax pen, two types of chocolates, some gummies, Dixie Elixirs punch and, of course, bud flower. At one lab, one of the products was a single quarter joint. “It was the strangest thing I’ve ever seen,” Arias remembers. “It was pretty hilarious, because it looked like something out of Cheech and Chong, like a little trumpet of weed.”

Each group of volunteers usually has some older members who have only smoked joints or pipes; they’re frequently surprised by all the new products. “They’ll look around at all the newfangled gadgets and laugh,” says Arias. “But for the younger users, it’s just so normal.”

Though the bud flower is often the most popular, it’s important for the lab that volunteers use different products. Arias and the paramedic keep track of what each volunteer consumes; the information will be used as a reference point later on in the training.

Randy Bott, 51, has never used a vape pen before, so he decides to try it. Bott is a friend of Shroyer’s; she told him about the green lab. He was motivated to volunteer in part because he wants to help officers make roads safer. But he’s also used marijuana in the past to treat a medical condition, and he’s intrigued by the idea of sampling some of the green-lab offerings.

Siblings Caitlin and Madison Smith (no relation to Anthony) are also volunteering; they both work in the cannabis industry. Caitlin is curious about how law enforcement officials determine the difference between alcohol and cannabis impairment. “Being a user of both,” she says, “I feel like you can’t compare them.”

Madison is an active Coloradan in his late twenties who enjoys outdoor activities, from duck hunting to geocaching. A friend of his recently got a DUI for marijuana, and he’s eager to help break down the stereotypes about typical stoners.

Upcoming Events

As the others consume and make small talk, Anthony Smith sits in the back of the RV and watches things progress. At one point, he goes outside to get away from the smoke; that’s when his daughter who lives out of state calls him. “I said, ‘I’m in a pot study,’” he reports. “She was like, ‘What is that?’ So I had to explain, ‘Look, we’re in this fourteen-foot trailer with a big cloud of smoke, and then we’re going to talk to cops for a while.’” His daughter’s general reaction: Colorado’s crazy.

Topics of discussion tonight range from rolling papers and the annual Bong-a-Thon to Martha Stewart and Snoop Dogg’s new TV show to cannabis consumption and driving. “It’s always interesting to see the dynamic as people keep partaking more,” Arias notes. “Usually by the end of the night, everyone’s just kind of giggling about the whole experience.”

Volunteers chat outside the green lab Winnebago.
Volunteers chat outside the green lab Winnebago.
Anthony Camera

The green lab is only part of the training that Halsor organizes. The first half of the day, which takes place in a small hotel ballroom, isn’t much different from any other work-related conference or seminar. When the officers arrive, they get packets and name tags and then settle in at tables stocked with DoubleTree notepads and water glasses.

From the start, law enforcement officials across the state and beyond have been interested in the ULM training and green lab. Halsor has held nineteen sessions to date, and each typically has twenty to thirty officers. This is an education that officers simply can’t get from anyone but Halsor.

“He’s quite well known around the law enforcement community in Colorado as both an entertaining and energetic instructor,” says Dave Copeland, a state trooper who teaches at the ULM trainings.

Many of the people who attend are drug recognition experts, or DREs. The DRE program is national; in Colorado, it’s headed up by the Colorado Department of Transportation. Among other things, officers who apply for DRE training have to show proficiency in DUI enforcement, including their ability to recognize impairment. Once DREs are certified, they have to renew that certification every two years. When officers who aren’t specially trained arrest someone because they believe the person is impaired but they can’t detect alcohol, they will call a DRE for an evaluation.

“We have a traffic-safety responsibility, and we have to look at ways to get our officers trained,” says Glenn Davis, CDOT highway safety manager. That’s where Halsor comes in. “I think he offers a really good service. He’s found a niche and he delivers a good product, a good training product,” Davis adds.

For Colorado DREs, CDOT is able to reimburse some of the cost of the ULM training, in part through National Highway Traffic Safety Administration funds — travel and expenses only, nothing actually involving cannabis. Depending on the session’s location, the total cost runs between $300 and $500 per student.

After a few hours of listening to Halsor talk about cannabis, the officers split up into groups to visit local dispensaries. This is another reason the DoubleTree is such an attractive venue for ULM training: It is close to many dispensaries, and the officers don’t have to descend on a single store en masse. Instead, they can fan out, and each group still gets to visit a few businesses.

Halsor always stresses that this is an opportunity not just to get information that will be useful during roadside tests, but also to ask regular cannabis users and people in the business the kinds of questions the officers might never get to ask otherwise. Later in the evening, they will be able to ask the volunteers about their cannabis consumption as well. So throughout the training, they can collect real information about cannabis products and culture in a relaxed environment.

“The intent of the first class was to help law enforcement and prosecutors improve their ability to detect, investigate and ultimately effectively prosecute marijuana DUI cases,” says Halsor. “But something interesting happened along the way.” Though the primary goal of the ULM trainings is still to teach officers how to prove impairment, he explains, the unintended benefit is that the sessions can help improve communications between two traditionally adversarial groups, breaking down barriers.

When Halsor’s team was first recruiting volunteers, people frequently asked why they should help police arrest other people. In other words, they wanted to know: What’s in it for the cannabis user?

“We quickly realized that was a question — and a legitimate question,” Halsor recalls.

ULM had an answer for those first volunteers, but no one on the team could know for sure that it would come true before that initial class. “The answer, and it’s still the answer to this day, is that now that we have a system that permits people to possess, consume and in some instances grow their own marijuana,” he says. “We have people out there who are going to be using this drug, and a fair public-safety question is: Should they drive?

“So the way we approached it is to say, for decades this has been an illegal drug. All that was required in those decades was that law enforcement had an indicator that you had used it,” Halsor continues. Law enforcement officers could develop probable cause with their noses, and “the mere fact that you had it, that was the crime.”

What the ULM team decided to convey to would-be volunteers was that, yes, your presence and participation in the green lab is helping these officers get better at detecting impairment, but it’s also helping to educate officers on when not to make an arrest.

There’s still a pervasive stereotype about the typical stoner. But especially in a state where recreational marijuana is legal, cannabis users are a diverse bunch of people — and law enforcement officers now recognize that. For volunteers, participating in the green lab is an opportunity to demonstrate that they are regular people who just happen to choose cannabis as their substance of choice.

For law enforcement officers, taking the training is a way to show that their interest is coming from a public-safety concern, not a desire to lock up stoners.

Traffic sergeant Bob Martin and another officer have come to this session from Arizona, where medical marijuana is legal but residents just voted against legalizing recreational marijuana. “I don’t think any of us have a moral objection,” Martin says regarding cannabis consumption. “It’s just our job. Clearly there are issues with smoking and driving.”

Halsor stresses that the volunteers are deserving of respect. “We want them to learn from each other,” he says.

The volunteers are also given advice. “You don’t have to act impaired, you don’t have to act unimpaired,” says Copeland, who’s also a DRE. “Just be yourself.”

Before they’d retired to the RV to dose, the volunteers had come into the DoubleTree to meet the trainees. Since some volunteers are still a little nervous even before they consume, this gives the officers and the volunteers an opportunity to establish a bit of a rapport. It also gives the officers a baseline view of the volunteers’ demeanor that they can use later when judging impairment.

There’s another baseline: The volunteers have their vital signs taken before the beginning of each lab. The paramedic records pulse, respiration and blood pressure; these will be measured again later. Significant differences in things like respiration and blood pressure are meaningful markers to DREs.

The volunteers also submit to an oral swab to see if they have anything else “on board” — any other substance, such as medication, in their systems. ULM uses a Dräger oral drug-testing device as a screening tool to measure this. The results won’t necessarily disqualify anyone — they’re volunteers, after all. If another substance is detected that might affect the way a volunteer responds to roadside sobriety tests, that’s part of the learning experience, too.

Anthony Smith (in hat) was the sober control.
Anthony Smith (in hat) was the sober control.
Anthony Camera

The stoned volunteers — and one control — now return to the hotel and spread out between two ballrooms, where they each take a seat in a corner. Anthony Smith, the sober control, grabs a chair in the back; the officers know there will be one sober person among the volunteers they observe, but they don’t know who it is. After the sixteen officers in the class split into groups of two or three, they move over to the volunteers they met earlier in the evening and start performing roadside tests.

They perform Standardized Field Sobriety tests — like the HGN (horizontal gaze nystagmus) test, the walk-and-turn, and the one-leg stand — that have been around since the mid-1970s. There’s another test called the modified Romberg, which officers use to check for balance issues and to assess someone’s internal clock. As the officers administer the roadside tests, they’re looking for eyelid tremors, body tremors, balance issues and the ability to focus and follow instructions. These are standardized clues they use for all traffic stops.

The green lab also teaches the officers to look for other details they need to support a DUI cannabis arrest, details that will help describe impairment to a jury. The lack of an equivalent to a Breathalyzer test can be frustrating, Copeland admits, but there’s more to the green-lab trainings than just compensating for that.

“One of the huge things for me is rapport building,” Copeland says. “I really, really strive, as an instructor, to get officers to build rapport, no matter who that person is.” Sometimes, he explains, being able to just get on the same level as a driver you’ve stopped is more helpful than the roadside tests.

And as this portion of the green lab continues, that’s what starts to happen. The officers start out standing as they talk with that first volunteer, assessing impairment. But as the night goes on, and as the officers move around to different volunteers, they often pull chairs over so that they can sit and really talk.

Colorado state trooper Nathaniel Grimm is one of the first trainees to take a seat by a volunteer. “It’s got to be kind of intimidating for them walking into this room and they’re sitting in a corner, surrounded by three cops towering over them,” he says. “I think it’s important to try and get on their level and try and make them feel comfortable.”

By the end of the lab, almost everyone — officers and volunteers alike — is sitting around in small circles talking. “In the class, these folks aren’t being arrested, so they can be blunt and totally truthful with the officers,” Copeland says. As a result, biases can change for officers, too. “What I love about the class is when they go and they realize [that] this person — this is their life, and there is a lot of knowledge, and they’re a good resource,” he adds.

Chris Halsor discusses marijuana with law enforcement officers.
Chris Halsor discusses marijuana with law enforcement officers.
Anthony Camera

At the end of every green lab, the ULM team asks volunteers for feedback.

Anthony Smith recognizes that his balance issues had affected his performance. “I know I didn’t do well on them,” he says of the roadside tests. Still, he’s surprised that some officers thought he showed signs of impairment — and that a few would have arrested him.

For his part, Bott knows he failed the heel-to-toe sobriety test, and that the officers might have arrested him. But he would have been fine with that — because he says he definitely shouldn’t have been driving after dosing. “As long as they got the information they needed to make the roadways safer,” he’s fine with how things went.

After they offer their assessments, the volunteers are driven safely home by either a sober friend or a member of the ULM team.

On the second day of training, the officers get their turn to offer feedback when Halsor and Copeland conduct a wrap-up session. They discuss each volunteer one by one, asking which officers got to interact with the volunteer when he or she was still sober. Then they ask the rest of the officers what they noticed during the roadside tests. Ultimately, they ask who would have arrested each volunteer. After the officers have shared their thoughts, Halsor and Copeland tell them what the volunteers’ vital signs and THC levels actually were at the end of the night.

There are some raised eyebrows when they hear that Anthony Smith was sober. “A few head nods, like, dang it, they got me,” reports Copeland, who thinks talking about the volunteer who was the control is a great way to remind officers that some signs that may show up during a roadside — signs that could also be caused by age and physical condition — are only a piece of the puzzle.

“I think it’s a very good reminder to everyone,” says Trent Heuertz, a state trooper from South Dakota here for the training. Heuertz is a DRE instructor, and says he makes it a point to teach new DREs that they can’t prove impairment from just one physical sign.

All of the officers have participated in wet labs, and they note that the green lab participants are much more relaxed and mellow than those who take part in the former. Apparently, the drunks are typically louder, more unpredictable and harder to corral.

The stoned participants may be more mellow, but they can be just as clueless. A shocking number think they would be fine to drive after dosing, Halsor says, but then they hear differently from the officers. Some volunteers accept this feedback, and some don’t. “It’s the daily chronic users that I think present the challenges,” he adds.

Since he started this business, Halsor says more acquaintances have “come out” to him, admitting that they use cannabis. Some of those confessions have surprised him — perhaps indicating that his work with ULM has broken down a few stereotypes that even Halsor didn’t realize he had. “Everybody wants to know what side I’m on,” he says. “I always tell them, I am the objective rational actor. I just walk down the middle. I think generally the public has changed its mind, and we’re seeing that all over the country. But there are collateral consequences, and there are some negative collateral consequences, some related to impaired driving.”

As Denver deals with the passage of Initiative 300, which will allow people to consume cannabis at some local businesses, the ULM trainings become even more important: Halsor is concerned that there’s more incentive for people to go out, consume marijuana socially and possibly drive afterward.

And with four more states just voting to legalize recreational marijuana, those consequences could grow as cannabis use becomes more widespread. Five years from now, Halsor could see green labs being conducted by law enforcement, and as common as wet labs. ULM could pave the way. “We want to be a vehicle to help propel the science,” he says.

Inside the RV, Laura Shroyer, DJ Morrison and Madison Smith consume some cannabis.
Inside the RV, Laura Shroyer, DJ Morrison and Madison Smith consume some cannabis.
Anthony Camera

DJ Morrison, a 38-year-old cook, former boxer and medical user who moved to Colorado in 2012, got a ride home after his second time as a volunteer at the lab.

“You still get that bit of paranoia,” he says of interacting with the officers, “but knowing that you’re not going to be in trouble and that they’re not in uniform kind of breaks the tension.”

In fact, the green lab has changed Morrison’s mind somewhat about police officers. In the past, the mere presence of police in a public place or on the street might have caused him to feel uneasy, he says. Now he wouldn’t be as guarded.

Strange as the evening was, he’d call it a positive experience. “I think people get the wrong perception when they think about marijuana,” he says, adding that he’s glad he got to help teach officers what a high person is like. He’d definitely volunteer again.

“I just really hope that people keep an open mind about the experience and what they’re actually trying to do with the green lab,” he says.


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