Workplace driving impairment: alcohol, drug and medication policies
Set fit for duty rules on alcohol, drugs, medicines and cannabis for employees who drive
Picture a field technician who arrives at 7 a.m. smelling of last night’s drinks. A sales rep started a prescription painkiller after back surgery. A delivery driver used legal cannabis the night before. Each one is holding company keys. What happens next depends on your plan.
Transportation incidents caused 1,937 of the 5,070 U.S. work deaths in 2024, more than any other type of event [1]. Impairment is part of that risk. In a National Highway Traffic Safety Administration (NHTSA) study of 7,279 seriously or fatally injured road users, 55.8% tested positive for alcohol, other drugs or both [2]. A positive result shows a substance was present, not that it caused the crash [2].
This guide blends the views of an occupational medicine physician, a toxicologist and a workplace safety professional. For the science, see our guides to alcohol impaired driving and drug- and medication impaired driving.
What "fit for duty" means for employees who drive
Fitness for duty is a simple promise: every work drive starts and ends with a driver who can drive safely. Define impairment broadly. Cover alcohol, illegal drugs, cannabis, prescription and over the counter (OTC) medicines, fatigue and illness.
Federal trucking rules take the same broad view. A commercial driver may not drive when fatigue, illness or “any other cause” makes it unsafe. A carrier may not require or permit it [4].
The Occupational Safety and Health Administration (OSHA) advises employers to adopt written policies on impaired driving [3]. Apply yours to everyone who drives for work, including managers, in company, rental and personal vehicles. It fits inside a broader workplace motor vehicle safety program.
Write alcohol and drug rules people can follow
DUI laws are a legal floor, not a safety line. For work driving, set the alcohol line at zero: none on duty, none in work vehicles, and none within a set window before driving.
Federal rules show what that looks like. Commercial drivers may not use alcohol within 4 hours before duty. They may not have any detectable alcohol while on duty or driving a commercial motor vehicle (CMV) [4]. Consider a longer window, such as no drinking the night before an early drive.
For drugs, ban illegal drug use, cannabis use or impairment while working, misuse of prescriptions and driving while impaired by any substance.
Fitness for duty policy outline
- Scope. Every employee and manager who drives for work, in any vehicle. Decide how contractors fit.
- Standard. Report ready to drive, free of impairment from alcohol, drugs, medicines, fatigue or illness.
- Alcohol. None on duty or in work vehicles. A no drinking window before driving of at least 4 hours.
- Drugs and cannabis. No illegal drugs, no cannabis use or impairment at work, no prescription misuse.
- Medicines. A private route to occupational health when a medicine might affect driving.
- Testing. Which tests, when and who reviews results, as the law allows.
- Speaking up. How to report concerns, with no retaliation.
- Supervisor response. Remove from driving, document, refer and arrange a ride.
- Help. The employee assistance program (EAP), treatment and return to work steps.
- Consequences. Clear and applied the same way to everyone.
- Review. Legal and HR review, yearly updates and a signed acknowledgment.
Commercial drivers: federal testing rules
If employees need a CDL to drive, the Federal Motor Carrier Safety Administration (FMCSA) rules in 49 CFR Part 382 apply. Testing procedures follow 49 CFR Part 40 [5].
Comparison compiled by Safety Behind the Wheel Foundation
Required tests for CDL drivers
| Test | When it happens | Key detail |
|---|---|---|
| Preemployment | Before the first safety sensitive work | A negative drug result is required [5, 6] |
| Random | Unannounced, spread through the year | Minimum yearly rates: 50% of driver positions for drugs, 10% for alcohol [5] |
| Reasonable suspicion | A trained supervisor sees specific signs | Alcohol test within 2 hours if possible; stop trying at 8 hours [5] |
| Post accident | Any death; injury or tow away with a citation | Alcohol within 8 hours, drugs within 32 hours [5] |
| Return to duty | After a violation and evaluation | Must be negative before driving again [6] |
| Follow up | After returning to duty | At least 6 observed tests in 12 months, extendable up to 4 more years [6] |
An alcohol level of .04 or higher is a violation. A result of .02 to .039 still means at least 24 hours off safety sensitive work [5]. Employers must query FMCSA’s Drug and Alcohol Clearinghouse before a driver starts and at least yearly after that [5].
Everyone designated to supervise CDL drivers needs at least 60 minutes of training on alcohol and 60 more on drugs [5]. Prescribed controlled substances, such as opioids, are allowed only when a practitioner who knows the driver’s history advises they won’t hurt safe driving [5].
Testing other employees: state law decides
For workers without a CDL, state law mostly sets the testing rules. Federal disability rules do not count a test for illegal drug use as a medical exam [9]. State laws, though, may limit who you test, when and for what.
Federal disability rules also let employers require compliance with the Drug Free Workplace Act of 1988 [9]. If you hold federal contracts or grants, ask counsel whether it applies. Either way, testing is one tool. Clear rules and trained supervisors do most of the daily work.
Prescription and over the counter medicines
The U.S. Food and Drug Administration (FDA) lists medicine types that can make driving unsafe. They include opioids, antianxiety medicines, sleeping pills, muscle relaxants and some antidepressants. Cold and allergy products with antihistamines, motion sickness medicines and cannabis or CBD products are on the list too [12]. Side effects such as sleepiness, blurred vision and dizziness can last into the next day [12].
Work driving data point the same way. In FMCSA’s study of serious large truck crashes from 2001 to 2003, prescription drug use was the third most common factor coded for trucks [13]. OTC drug use was coded for 17%. Those trucks were 1.3 times as likely to be assigned the critical reason for the crash [13]. A coded factor shows presence, not cause [13].
Toxicologists watch for risk windows: a first dose, a dose increase, a new combination, any alcohol on top and the morning after a sedating nighttime pill.
Privacy: send medicine questions to occupational health
Under Americans with Disabilities Act (ADA) rules, medical questions to current employees must be “job related and consistent with business necessity” [9]. Answers belong in separate confidential medical files. Supervisors learn only about needed work restrictions and accommodations [9].
So ask drivers to raise medicine concerns with occupational health or their own clinician. A clinician decides “fit,” “fit with limits” or “not fit to drive today.” The supervisor hears only the limit. Never tell a worker to stop a prescribed medicine. FDA advises talking with a health professional first [12].
Cannabis: legal is not the same as fit to drive
Legal purchase says nothing about readiness to drive. Base your rule on impairment and on use near work time, not on state law alone.
Testing has real limits. NHTSA reports that impairment peaks about 90 minutes after smoking, when blood THC has already fallen more than 80% [14]. Blood THC does not reliably predict impairment [14]. Urine can show use from days or even weeks earlier and cannot prove someone was under the influence [14]. In 2017, NHTSA found no proven roadside test for cannabis impairment like the alcohol breath test [14].
So treat a positive urine test as evidence of use, not proof of impairment now. Pair any test with documented observations. A simple rule for employees: no cannabis on any day you drive for work.
For CDL drivers, there are no exceptions. As of its December 2025 notice, DOT said marijuana remained a Schedule I drug while federal rescheduling was pending. Testing continues [7]. DOT also says CBD use does not explain away a positive marijuana test [8].
Making it safe to report a concern
People hesitate to report a coworker. Make it easy and fair:
- Offer several channels: a supervisor, the safety team, HR or a confidential line.
- Ask for facts, not labels: “slurred speech, smelled of alcohol at 7:10 a.m.,” not “he’s drunk.”
- Protect reporters from retaliation, and act on every report.
- Welcome self reports. A worker who says “I’m not fit to drive today” before driving should get a ride and support, not punishment for speaking up.
The supervisor's 4 steps: observe, remove, document, refer
- Observe. Note specific signs in appearance, behavior, speech and odor, with times. Low blood sugar or a stroke can mimic intoxication, so if you’re unsure, call 911.
- Remove. Take the worker off driving and other safety sensitive tasks now. Collect the keys calmly and privately.
- Document. Write what you saw and heard soon, ideally with a second trained witness. Stick to facts.
- Refer. Call HR and occupational health. Arrange testing if your policy and the law allow, and mention the EAP. For CDL drivers, follow Part 382 timelines. The supervisor who makes the call may not run the alcohol test [5].
OSHA notes that reasonable suspicion training may be required for supervisors [3]. Give every supervisor of drivers the same training as CMV supervisors, plus how to spot medical mimics.
Transportation alternatives: getting everyone home
Plan rides before you need them:
- Rideshare or taxi paid by the company, with a code or reimbursement set up in advance.
- A sober coworker who drives the employee home, leaving the work vehicle parked for later pickup.
- A family member pickup, with the employee’s consent.
- Mobile testing at the site, so no one travels while impaired.
- Reschedule or reassign routes and jobs, so no one feels pressure to drive.
For remote workers, the rule is simple: stay put and call in. The company sends a ride.
After a crash: post incident steps where lawful
Care comes first: call 911, protect the scene and get medical help. For CDL drivers, post accident tests follow federal triggers and time limits. A driver who must be tested may not drink alcohol for 8 hours or until tested [5].
For other workers, OSHA bars retaliation against employees for reporting work injuries [15]. OSHA’s 2018 memo says most drug testing is still allowed. Examples include random tests, tests required by state workers’ compensation or federal law and tests unrelated to injury reporting [15]. Testing after an incident to find a root cause is allowed when you test everyone whose conduct could have contributed, not just the injured worker [15]. Testing meant to punish reporting is not [15]. State law may add rules. Minnesota allows reasonable suspicion testing after a work accident [10].
Look beyond the test result. Ask about schedules, sleep, illness and medicines, too.
Support, return to work and who does what
For CDL drivers, a violation means removal, a substance abuse professional evaluation, education or treatment, a return to duty test and follow up tests [6]. ADA rules do not protect current illegal drug use. People in or done with supervised rehabilitation who no longer use may be protected [9]. For others, use an occupational health clearance and a written return to work plan.
Comparison compiled by Safety Behind the Wheel Foundation
| Role | Owns | Steers clear of |
|---|---|---|
| Supervisor | Observing, removing, documenting, arranging a ride | Diagnosing or judging medicines |
| HR | Policy, consistency, discipline, labor agreements | Putting medical details in personnel files |
| Occupational health | Fitness decisions, medicine reviews, return to work clearance | Sharing diagnoses with managers |
| Safety team | Training, crash reviews, trend tracking | Reviews that stop at blaming the driver |
| Legal counsel | State testing, privacy, cannabis and disability law | Waiting for a dispute to review policy |
| EAP | Confidential counseling and referral | Sharing details without consent |
Frequently asked questions
Can my employer drug test me if I don’t have a CDL?
Often yes, but state law decides how. Minnesota, for example, requires a written policy and limits random tests to safety sensitive jobs [10]. Check your company policy and your state labor department.
Can I be fired for legal cannabis use on my day off?
It depends on your state and job. New York and Minnesota protect lawful off duty use, with exceptions for impairment at work and federal requirements [10, 11]. CDL drivers have no such protection under DOT rules [7].
Do I have to tell my employer about my prescriptions?
ADA rules limit employer medical questions to those that are job related and consistent with business necessity [9]. A good policy asks only whether a medicine might affect driving and sends that to occupational health.
What’s the alcohol limit for driving a company car?
State DUI law sets the legal limit, but a strong safety policy sets zero for work driving. Commercial vehicle drivers may have no detectable alcohol on duty [4]. For CDL drivers, .04 is also a testing violation [5].
What should I do if a coworker seems impaired before a drive?
Tell a supervisor right away and describe what you saw. Don’t get physical. If they drive off and seem dangerous, call 911.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Define fitness for duty broadly and set alcohol rules stricter than DUI law. Route medicine questions to occupational health. Train supervisors to observe, remove, document and refer, with a ride home always ready.
Related articles
- Workplace motor vehicle safety program: a step by step employer guide
- Drug and medication impaired driving: know your risk before you drive
- Alcohol impaired driving: know the risks and plan a sober ride home
- Drug and cannabis DUI laws by state: THC limits, testing and medicines
- Work driving fatigue: safer shifts, schedules and trip rules for employers
Sources and further reading
- 1U.S. Bureau of Labor Statistics. Census of Fatal Occupational Injuries Summary, 2024. February 19, 2026. bls.gov/news.release/cfoi.nr0.htm
- 2Thomas FD, Darrah J, Graham L, et al. Alcohol and Drug Prevalence Among Seriously or Fatally Injured Road Users. NHTSA, DOT HS 813 399. December 2022. rosap.ntl.bts.gov/view/dot/65623
- 3Occupational Safety and Health Administration (OSHA). Motor Vehicle Safety: Employers. No date shown; accessed October 3, 2026. osha.gov/motor-vehicle-safety/employers
- 4Electronic Code of Federal Regulations. 49 CFR Part 392, Subpart A (sections 392.3 and 392.5). Accessed October 3, 2026. ecfr.gov/…/part-392/subpart-A
- 5Electronic Code of Federal Regulations. 49 CFR Part 382, Controlled Substances and Alcohol Use and Testing (including sections 382.201, 382.207, 382.209, 382.213, 382.301 to 382.307, 382.505, 382.603 and Subpart G). Up to date as of September 30, 2026. ecfr.gov/…/part-382
- 6Federal Motor Carrier Safety Administration (FMCSA). What Tests Are Required and When Does Testing Occur? December 10, 2024. fmcsa.dot.gov/…/what-tests-are-required-and-when-does-testing-occur
- 7U.S. Department of Transportation, Office of Drug and Alcohol Policy and Compliance (ODAPC). DOT’s Notice on Testing for Marijuana. December 19, 2025. transportation.gov/odapc/marijuana-notice
- 8U.S. Department of Transportation, ODAPC. DOT “CBD” Notice. February 18, 2020. transportation.gov/odapc/cbd-notice
- 9Electronic Code of Federal Regulations. 29 CFR Part 1630, Regulations to Implement the Equal Employment Provisions of the Americans with Disabilities Act (sections 1630.3, 1630.13, 1630.14 and 1630.16). Up to date as of September 25, 2026. ecfr.gov/…/part-1630
- 10Minnesota Office of the Revisor of Statutes. Minnesota Statutes 2025, sections 181.938, 181.950 and 181.951. Accessed October 3, 2026. revisor.mn.gov/statutes/cite/181.951
- 11New York State Senate. New York Labor Law Section 201-D (subdivisions 2 and 4-a). Last revised September 8, 2023; accessed October 3, 2026. nysenate.gov/legislation/laws/LAB/201-D
- 12U.S. Food and Drug Administration (FDA). Some Medicines and Driving Don’t Mix. Consumer update. March 12, 2024. fda.gov/consumers/…/some-medicines-and-driving-dont-mix
- 13FMCSA. The Large Truck Crash Causation Study: Analysis Brief. July 2007. fmcsa.dot.gov/…/large-truck-crash-causation-study-analysis-brief
- 14NHTSA. Marijuana-Impaired Driving: A Report to Congress. DOT HS 812 440. July 2017. nhtsa.gov/…/812440-marijuana-impaired-driving-report-to-congress.pdf
- 15OSHA. Clarification of OSHA’s Position on Workplace Safety Incentive Programs and Post-Incident Drug Testing Under 29 C.F.R. §1904.35(b)(1)(iv). Memorandum. October 11, 2018. osha.gov/laws-regs/standardinterpretations/2018-10-11
This article reflects the safety priorities of occupational medicine, toxicology and workplace safety. It is general education, not legal, medical or professional advice for any person or company. Employers should have policies reviewed by employment counsel. Workers should talk with their clinician about their medicines. Laws, testing rules and data change, so verify details with official sources. Reviewed October 2026.
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