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Marijuana legalization, trucking, and the future of drug testing

This article was published by Overdrive, The Voice of the American Trucker

Alex Lockie

May 9, 2024

Just a week after President Joe Biden's administration began winding down a long road toward marijuana rescheduling, Senate Democrats introduced a bill that would deschedule it entirely. That is, the bill would remove marijuana's "controlled substance" status altogether.

Needless to say, after five decades of the federal government treating marijuana like it was cocaine or heroin, things are rapidly evolving with America's favorite illicit drug. Evolving, but not changing. As anyone in trucking knows, the government moves slowly. 

Previous reporting on marijuana rescheduling highlighted attorney Brian Vicente's sobering commentary that, even if the feds reschedule marijuana, recognizing its medical value and creating a pathway for Food and Drug Administration approval of products derived from it, legitimate and approved prescriptions remain many years down the road.  

But descheduling it entirely? In light of the Senate's feint in that direction, what might something closer to federal legalization really mean for trucking? And how might required professional driver drug testing evolve to accommodate? 

Time will tell for certain, but evolution seems inevitable, according to closer watchers, who feel it's time for regulators and trucking companies to really engage with the substance of the national conversation around marijuana. 

Paul Armentano, deputy director of the National Organization for Reform of Marijuana Laws, has published extensively on marijuana law, and even its impact on the trucking world, a consistently hot topic. A 2023 American Transportation Research Institute report found 60% of carriers had seen an increase in positive drug tests and test refusals over the last five years, and that 62% of carriers thought new federal regulations were needed to deal with states increasingly legalizing and decriminalizing marijuana.

Unfortunately, in Armentano's view, neither the Biden administration's rescheduling efforts nor the Senate Democrats' descheduling would really address the federal regulations that impact trucking. 

The Senate Democrats' "bill seeks to legalize marijuana, but I think that using that terminology causes undue confusion," he said. "Some people presume the federal government is going to make marijuana legal nationwide, but that's not what the Senate bill would do. That’s not what any proposed federal legislation would do."  

Instead, the bill would simply repeal the federal prohibition on marijuana, much like when it repealed the short-lived prohibition on alcohol nearly a century ago, he said. Armentano compared "legalized" weed under this bill to alcohol or tobacco. Neither substance is "scheduled" as a controlled substance by the feds, and instead they're each governed by a "50-state patchwork system," he said. 

Think of each state and/or locale's alcohol-law quirks. Some won't allow Sunday sales, some bar sales at a grocery store. Others, still, sales before a certain time of the morning.  

"The federal government still provides oversight, specifically involved in tax collection and enforcement of interstate commerce" and rules around labeling, Armentano said, but for the most part, states make the rules on alcohol. Rescheduling, according to Armentano, would not provide states the flexibility to administer cannabis as they see fit, but descheduling would. But he doesn't like the chances of that descheduling bill in the Senate. "It's not going anywhere," he added. "It's symbolic." 

In either case, he emphasized, marijuana is part of CDL holders' drug tests for other reasons entirely. The substance was "included among the drugs to be tested for" under the DOT's Revised Drug and Alcohol Testing Rule in 1988. Neither rescheduling nor descheduling would remove it from the test. 

"Those regulations would need to be revisited by either the DOT or by Congress, and a decision would have to be made," said Armentano, in order to change anything about treatment of marijuana there. 

Yet If rescheduling efforts detailed in the prior report succeed, change could be necessary. Within a decade it's not unlikely that some U.S. truck drivers could hold valid prescriptions for FDA-approved marijuana or CBD, much like today a truck driver can have a prescription for opioid-based pain killers, even test positive for opioids if it's properly documented, without career-killer fears.

Driving impaired is an entirely different issue. Driving impaired in any way remains illegal, and no serious regulatory or legislative effort will seek to change that. The problem is that with suspected marijuana use, methods of measuring impairment where it's needed -- at the point of the suspicion of impairment -- aren't nearly where they need to be to ensure accuracy and efficacy at the roadside.  

Marijuana legalization and the future of drug testing 

The state of Massachusetts has allowed recreational marijuana use since 2016, when Dr. Michael Milburn embarked on a quest to find a better way to test drivers for impairment by the substance. In trucking, the notion of a "weed breathalyzer" has been kicked around as a possible silver bullet to solve the thorny roadside testing problem. Instead of ruining a driver's career over mislabeled gas station CBD products, inspectors could test what actually matters: Is the driver impaired by substances while operating the vehicle?

Yet both Milburn and Armentano stressed that measuring THC, the psychoactive molecule in marijuana, in breath doesn't prove intoxication, and that there's no effective roadside measuring tool like a breathalyzer. Furthermore, because THC dissolves in fat and not water, it stays in the  body for weeks or months. That, combined with marijuana's widespread popularity and availability, makes it the easiest and most frequently spotted drug in urine tests required by DOT. A cocaine user, for example, might use the drug and test negative in three days. A marijuana user might test positive more than a month after using even a small amount.

Almost three-quarters of all positive drug tests in the Drug and Alcohol Clearinghouse are for marijuana. Positive urine tests do not prove that the driver ever stepped on the pedal impaired, according to Milburn.

Milburn advocates for an approach to roadside impairment testing different than the seeming panacea of breathalyzers. "If you want to assess cognitive motor impairment, you should do that by measuring cognitive motor behavior," said Milburn, who has 40 years of experience in psychology and research methods. He did a "deep dive into driving impairment literature." There he located the main capacities necessary for driving that are impaired by alcohol and cannabis. He designed an app called Druid "to measure that. It integrates a bunch of different measures into a single impairment score that's highly reliable."

The app prompts users to take a series of tests: Tapping little squares and circles that pop up on-screen to test reaction time and cognition, standing on one foot without shaking the phone too much, and others. Users of the app get an impairment score from around 25 to 75. 

Sober "fighter jet pilots might score around 25, or athletes like gymnasts or figure skaters, super balancers, get really low scores of maybe 28 or 29," he said. "Most people [score] in the high 30s and low 40s. A score of 55 or more generally indicates impairment." Likewise, a score 5 points higher than an individual's baseline can reliably indicate impairment, he added.   

News editors usually beat fighter jet pilots in terms of poise and dexterity, but this author took the tests and came in at 40. Druid has business customers and resellers of the product that test first responders, warehouse and other infrastructure workers, and Milburn said the tool has been effective so far. 

For roadside enforcement, the product could be reliable when dealing with someone who hasn't established a baseline previously, Milburn said, with repetition of the tests. (Impaired minds don't learn at the same clip as sober ones.) For maximum reliability, he suggested, drivers could establish their baseline score upon getting their CDL. 

Real impairment is a difficult nut to crack, including impairment from marijuana use. Milburn noted some big-time cannabis users don't see their scores go down at all when they're high. Furthermore, impairment can come from all kinds of activities, not just drug use. "Research shows actually that people’s reaction time can start slowing two or three days before onset of symptoms of a viral illness," he said. Of course, there's no law against operating a CMV when you're going to be sick the day after tomorrow. 

"A number of state that have legalized marijuana have wisely moved to also enact changes to state law that greatly change the way workplace drug testing is done," said Armentano. "In states like New York and California and several others, employers can no longer sanction or refuse to hire employees because they test positive for the past presence of marijuana."

At the federal level for now, though, there's "not even a whole lot of conversations" around changing drug testing policy, Armentano said.  In fact, the one current conversation centers around hair drug testing, which has even less connection to actual impairment

Yet the question of just how to approach the substance, he suggested, is coming for trucking companies and regulators sooner than later.  


Overdrive is the premier magazine for leased owner-operators and independent owner-operators. It presents business and equipment features relevant to trucking owner-operators and small fleets, as well as trucking news, truck driving jobs and other trucking industry information of interest to the independent contractor. Overdrive, The Voice of the American Trucker, has been published since 1961.


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