Medical Cannabis and Driving, Work and Drug Tests

You have a driver's license, a job and maybe a CDL, and you want to know whether a medical cannabis card could put any of them at risk. That is a smart thing to ask before your evaluation, not after. This guide gives general information, not legal advice, so you know which questions to take to your employer, your union or a lawyer.

Cannabis and Driving

Cannabis can slow your reactions and affect how you move and judge what is around you. The CDC lists slower reaction time and decision making, poorer coordination and distorted perception among the ways it affects driving. Using cannabis with alcohol or other drugs at the same time can make impairment worse.

People often feel less affected than they are. The National Highway Traffic Safety Administration (NHTSA) says impaired drivers can't accurately judge their own impairment, which is why no one should drive after using any impairing substance. The CDC adds that it is hard to link the amount of THC in a person's body to how impaired that one person is. So there is no safe number to aim for.

A few habits help. Don't drive, ride a snowmobile or ATV, or run machinery after using cannabis until the effects have fully worn off. Plan rides ahead on days you use it. Ask about your state's rules for carrying cannabis products in a vehicle, because they are set by state law.

Where Federal Law Stands in 2026

Federal law changed in 2026, but not as much as some headlines suggested. A federal final rule that took effect April 28, 2026 moved marijuana in FDA-approved drugs, and marijuana covered by a state medical marijuana license, from Schedule I to Schedule III of the Controlled Substances Act. Other marijuana, including recreational products, stayed in Schedule I. A separate proposal to move all marijuana to Schedule III went to a DEA hearing in the summer of 2026 and was still pending when this guide was written.

Schedule III drugs are still controlled substances under federal law. The change does not make cannabis legal for every purpose, and it does not change impaired driving laws. It also does not, on its own, rewrite your employer's drug policy. The rules are new and may keep changing, so check with your employer or a lawyer before you rely on them.

Work Rules and Safety-Sensitive Jobs

Most employers set their own drug and alcohol policies, and state laws on how far those policies can go differ. MedlinePlus notes that in some states, employers may still be able to discipline you for a positive cannabis test even where cannabis is legal. Your employee handbook and HR team are the best places to start.

Some jobs carry stricter rules because other people's safety depends on you. These are often called safety-sensitive jobs. Examples include:

• Transportation jobs covered by U.S. Department of Transportation (DOT) testing, such as truck drivers with a CDL, school bus drivers, pilots, train crews and pipeline workers.
• Federal jobs and some federal contractor roles, which may follow federal drug-free workplace rules.
• Health care, childcare, heavy equipment and similar roles, where employer or licensing rules may bar any use.

DOT has been clear for years. In a notice last updated December 19, 2025, DOT said it remains unacceptable for safety-sensitive employees covered by its testing rules to use marijuana, and that its testing process would not change until rescheduling is complete. If you hold a DOT-regulated job, talk with your employer's drug and alcohol program contact before you apply for a card.

Drug Tests and THC

Drug tests look for signs of a drug in your body. They do not measure whether you are impaired right now. MedlinePlus explains that tests can find signs of drugs taken hours to several days or more before the test, and NHTSA notes that the presence of a drug doesn't necessarily mean a person is impaired.

That cuts both ways. You may feel completely normal and still test positive days later. How long THC stays detectable varies from person to person, so no one can promise you a date when you will test clean. And under DOT rules, a medical cannabis recommendation is not accepted as a valid medical explanation for a positive result.

If your job tests, ask HR what happens after a positive result. Some employers offer a review, some have a zero-tolerance rule, and some treat medical use differently. Knowing the answer ahead of time is far better than finding out after a test.

Questions to Settle Before Your Visit

You don't need every answer before you book. But a little homework can save you from a choice you regret. Use this checklist:

• Read your employer's drug and alcohol policy, including anything it says about medical cannabis.
• Find out whether your job is safety-sensitive, DOT-regulated, federal or federally contracted.
• Ask HR, your union or a lawyer how a positive test would be handled. You can ask in general terms.
• Check any rules tied to a professional license, such as nursing or commercial driving.
• Plan how you will get around without driving on days you use cannabis.
• Write down your questions about timing, driving and side effects.
• Bring your medical records and a full medication list to the evaluation.

At your visit, Dr. Charlotte Ewals will ask about your work and driving as part of your safety review. She decides whether certification is medically appropriate, and she can explain the health side. She can't tell you how your employer or a court will treat your situation, and she won't guess.

Next Steps

Learn how our medical cannabis evaluations work, then read about cannabis and medication interactions and when medical cannabis may not be right for you. When you feel ready, book a visit or call Will at (218) 274-4500 with questions.