The American Trucking Associations (ATA) says it’s “deeply concerned” about the potential impact of federal marijuana rescheduling on drug testing programs for drivers—and it’s asking the secretary of the Department of Transportation (DOT) for clarity around the policy change.

In a letter sent to DOT Secretary Sean Duffy on Thursday, ATA’s chief operating officer, Dan Horvath, said the industry group wants “information regarding whether the DOT will retain the authority and capability to test for marijuana use by commercial motor vehicle (CMV) drivers and other safety-sensitive transportation workers” if cannabis is moved from Schedule I to Schedule III of the Controlled Substances Act (CSA).

Of course, that policy hasn’t been enacted yet. And while President Donald Trump said recently he’ll be making a decision on the pending proposal within weeks—after endorsing the reform on the campaign trail last year—it remains to be seen whether he intends to follow through on rescheduling.

Horvath said ATA does “not hold a formal position on marijuana legalization or deregulation,” but “we are deeply concerned about the safety risks of rescheduling marijuana without explicit safeguards to preserve the necessary testing authority and technical requirements for DOT-regulated safety-sensitive workers.”

The concern lies in the potential removal of mandatory federal drug testing guidelines under the U.S. Department of Health and Human Services (HHS) that DOT must currently comply with if cannabis is moved to Schedule III.

“If so, without clear measures to ensure DOT’s program retains–and is equipped to execute–marijuana testing authority, such a federal policy shift could have serious consequences for highway safety and the integrity of the national transportation network,” the letter says. “This risk is exacerbated by the fact that there is currently no proven, widely accepted standard to determine marijuana impairment at roadside or before a driver begins operating a vehicle, making it far more difficult to prevent impaired driving.”

“The risks and potential safety implications of such a gap in testing authority are well-documented,” Horvath said, pointing to data on the rate of positive THC tests among drivers and studies that he claimed demonstrate an increase in traffic fatalities following state-level legalization.

“ATA has repeatedly conveyed these concerns—and our request for clarity on potential impacts to the DOT testing program—to the Department under the previous administration, both through formal letters and in-person discussions,” he wrote in the letter, which was first reported by Transportation Topics.

Horvath also noted that while former Transportation Secretary Pete Buttigieg told a congressional committee last year that rescheduling wouldn’t impact drug testing regulations, ATA “never received a response to our correspondence explaining the basis for this position or detailing how DOT intended to address any impacts to the program.”

“Given the heightened public attention to marijuana policy and the possibility of a federal rescheduling of marijuana in the near term, we are requesting clarity on DOT’s plans to address such a change. Additionally, we urge DOT to proactively coordinate with HHS, [the Department of Justice], and relevant lawmakers to ensure that any federal policy shift preserves the authority, tools, and technical capacity necessary to continue testing DOT-regulated safety-sensitive workers.”

Meanwhile, a policy paper from a pair of companies in the trucking industry that was released in April says the sector was short about 80,000 drivers last year—an issue it asserts was exacerbated by workers testing positive for marijuana under DOT’s strict, zero-tolerance drug policy.

Moving marijuana to Schedule III “could have significant implications for DOT regulations and drug testing protocols,” the paper says—for example, by acknowledging legitimate medical use and potentially reducing social stigma—but it wouldn’t necessarily ease restrictions.

DOT drug screening programs typically use urine-based testing, but the report says that saliva and hair follicle testing offer benefits over that standard. It also notes that there’s “currently no widespread test to determine if a driver is currently under the influence of a drug like THC.”

The department finalized new testing policies in 2023 to allow oral saliva drug testing as an alternative to urine-based tests. Late last year, critics lamented that more than a year and a half after finalizing the rule, federal officials had yet to set up the infrastructure necessary to allow the new testing procedure to be used.

Congressional lawmakers at hearings in March heard from representatives of the trucking industry, who called for wider use of hair-follicle testing in the industry. The chair of the National Transportation Safety Board (NTSB), meanwhile, recommended better education for drivers.

In April, meanwhile, the U.S. Supreme Court ruled in favor of a trucker who sued a cannabis company after he was fired over a positive THC test that he said was caused by consuming a hemp-derived CBD product.

Separately, a Substance Abuse and Mental Health Services Administration (SAMHSA) official downplayed criticism from the CEO of a drug-testing company that more widespread use of saliva-based drug testing “means truckers who use cannabis will be able to do so with near impunity, as long as they avoid a drug test for a couple of days.”

The transportation industry also advised Congress in January that if marijuana is federally rescheduled, businesses want assurances that they won’t have to forgo zero-tolerance drug policies for drivers—while stressing that a key problem for the sector is a lack of technology to detect impaired driving.

A 2023 congressional report for a Transportation, Housing and Urban Development, and Related Agencies (THUD) bill said that the House Appropriations Committee “continues to support the development of an objective standard to measure marijuana impairment and a related field sobriety test to ensure highway safety.”

A year earlier Sen. John Hickenlooper (D) of Colorado sent a letter to the DOT seeking an update on that status of a federal report into research barriers that are inhibiting the development of a standardized test for marijuana impairment on the roads. The department was required to complete the report under a large-scale infrastructure bill signed by then-President Joe Biden, but it missed its reporting deadline.

Meanwhile, National Transportation Safety Board (NTSB) last year warned that marijuana rescheduling could create a “blind spot” with respect to drug testing of federally regulated workers in safety-sensitive positions.

At a House committee hearing, then-DOT Secretary Buttigieg had referenced concerns from ATA “about the broad public health and safety consequences of reclassification on the national highway system and its users,” which the trucking association voiced in a letter to the secretary.

Current federal law mandates that commercial drivers abstain from cannabis, subjecting them to various forms of drug screening, from pre-employment to randomized testing.

In June 2022, meanwhile, an ATRI survey of licensed U.S. truck drivers found that 72.4 percent supported “loosening” cannabis laws and testing policies. Another 66.5 percent said that marijuana should be federally legalized.

Cannabis reform advocates, meanwhile, have also called on federal officials to change what they call “discriminatory” drug testing practices around the trucking industry.

A top Wells Fargo analyst said in 2022 that there’s one main reason for rising costs and worker shortages in the transportation sector: federal marijuana criminalization and resulting drug testing mandates that persist even as more states enact legalization.

Then-Rep. Earl Blumenauer (D-OR) sent a letter to the head of DOT in 2022, emphasizing that the agency’s policies on drug testing truckers and other commercial drivers for marijuana are unnecessarily costing people their jobs and contributing to supply chain issues.

The 2022 ATRI report noted that research into the impact of cannabis use on driving and highway safety is currently mixed, complicating rulemaking to address the issue. A separate 2019 report from the Congressional Research Service (CRS) similarly found that evidence about cannabis’s ability to impair driving is inconclusive.

Read ATA’s letter on marijuana rescheduling and drug testing below: