DOT Drug Testing Program: 49 CFR Parts 40 and 382

The DOT drug testing program, set out in 49 CFR Part 40 and Part 382, requires anyone who holds a commercial driver’s license and operates a qualifying vehicle to submit to drug and alcohol testing at six defined moments, and it removes that driver from safety-sensitive work the instant a test comes back positive or is refused.¹ The rules apply the same way to a company driver, a leased driver, and an owner-operator working alone, and the consequences of a violation follow the driver through the FMCSA Clearinghouse regardless of which carrier they work for next.

Who the Rules Cover

Part 382 reaches every person who operates a commercial motor vehicle in interstate or intrastate commerce and is subject to CDL requirements. A commercial motor vehicle for these purposes falls into one of three groups: any vehicle or combination rated at 26,001 pounds or more, any vehicle designed to carry 16 or more passengers (driver included), or any vehicle of any size hauling placarded hazardous materials.¹

The definition of “driver” is broad on purpose. It captures full-time and part-time employees, casual and intermittent drivers, leased drivers, and independent owner-operators. If you employ only yourself, you still have to sit in a random testing pool of at least two covered employees, which in practice means signing on with a consortium or third-party administrator. Consortium fees for a solo owner-operator typically run about $100 to $200 a year, depending on the provider.²

When You Will Be Tested

Federal rules require testing at six distinct points. Some are scheduled, some are not, and knowing which is which matters.

Before You Start

Before performing any safety-sensitive work for a new employer, you must take a drug test and get a verified negative result back. No employer may put you on the road until the Medical Review Officer or consortium confirms the negative.³ Alcohol testing is not required pre-employment, though an employer may add it.

Random Selection

Every covered driver sits in a random pool. Selections are made by a scientifically valid method, spread across the year, with every driver having an equal chance every time.⁴ These are unannounced. For FMCSA-regulated drivers in 2026, employers must randomly test at least 50 percent of their pool for drugs and 10 percent for alcohol each year.⁵ Rates under FAA, FRA, and other DOT modes can differ.

After an Accident

Not every crash triggers a test. When the accident involves a fatality, a test is mandatory regardless of fault and regardless of whether anyone was cited. For non-fatal accidents, a test is required only if you received a moving traffic violation and either someone was injured seriously enough to need immediate treatment away from the scene, or a vehicle had to be towed for disabling damage.⁶

The clock is tight. Alcohol testing must happen within eight hours. If more than two hours pass, the employer must document the delay. Drug testing must happen within 32 hours; after that, the employer stops trying and writes up why. Don’t drink for eight hours after the accident, or until tested, whichever comes first.⁶

Reasonable Suspicion

A trained supervisor can order a test based on specific, contemporaneous observations of your appearance, behavior, speech, or body odor. The supervisor has to document the observations and must have witnessed them during, just before, or just after your on-duty period. That’s a different standard from “actual knowledge,” which means the employer directly saw you use, got a citation for you involving impairment, or heard you admit it.⁷

Return-to-Duty and Follow-Up

Any driver who has violated the rules must pass a return-to-duty test before going back to safety-sensitive work, and then complete a follow-up testing plan set by a Substance Abuse Professional. The SAP must order a minimum of six unannounced tests in the first 12 months back on duty, and can extend follow-up testing for up to 48 additional months.⁸

What the Test Actually Screens For

DOT tests look for exactly five drug classes. A lab handling a DOT specimen is prohibited from testing for anything else:⁹

Marijuana metabolites (THC)
Cocaine metabolites
Amphetamines
Opioids
Phencyclidine (PCP)

The specimen is either urine or oral fluid. Employers pick one method per testing event and can switch to the other mid-collection if something goes wrong, such as a urine temperature outside the 90 to 100 degree Fahrenheit range or a donor who can’t produce enough saliva.¹⁰ Oral fluid collection counts as directly observed for all purposes under the regulation, and it captures more recent use than urine does. Instant point-of-collection devices are not authorized. Every specimen has to go to an HHS-certified laboratory.

An initial immunoassay screen at or above the cutoff triggers a confirmatory test by gas chromatography-mass spectrometry or a similar advanced technique. That second test identifies the specific substance and its concentration, which is what eliminates most false positives. A result below the confirmatory cutoff is reported as negative.

Alcohol testing runs on a two-tier scale. A breath alcohol concentration of 0.02 or higher but below 0.04 is not a full violation, but the employer must pull you off safety-sensitive duty until your next regularly scheduled shift or for at least 24 hours, whichever is longer.¹¹ A result at 0.04 or higher is a full violation, with the same consequences as a positive drug screen.

What Counts as a Refusal

Drivers who think they can stall or maneuver their way out of a test almost always get counted as refusing. A refusal carries the same weight as a confirmed positive: it goes on your Clearinghouse record, it triggers the SAP process, and it blocks you from safety-sensitive work until you complete return-to-duty. The regulation lists conduct that counts as refusal:¹²

Not showing up for a test within a reasonable time after being directed to.
Leaving the collection site before the process is complete.
Failing to produce enough urine or saliva when directed, when a medical evaluation finds no physical reason for the failure.
Declining to allow a directly observed collection when one is required.
Refusing to empty pockets, wash hands, remove items from the mouth, or otherwise cooperate with collector instructions.
Possessing a prosthetic or other device that could interfere with the collection.
Admitting to the collector or MRO that you adulterated or substituted the specimen.

Direct observation of a urine collection means an observer of the same gender watches you produce the specimen. It’s required in specific situations: any return-to-duty or follow-up test, a specimen the lab reported as invalid with no adequate medical explanation, a negative-dilute result with very low creatinine, or a cancelled result because the split couldn’t be tested. It also happens on the spot if the original specimen was out of temperature range or looked tampered with.¹³ Refusing the observed collection counts as refusing the test.

What Happens After a Positive Test or Refusal

Immediate removal from safety-sensitive duties. The employer has to pull you the moment the report arrives. There is no grace period and nothing to negotiate.

From there, the employer refers you to a Substance Abuse Professional. The referral, evaluation, and any treatment follow the procedures in 49 CFR Part 40, Subpart O.¹⁴ The SAP does a face-to-face assessment and prescribes a course of education or treatment, which might be a brief course or something more intensive. You pay for the SAP evaluation and any treatment out of pocket, typically a few hundred to a couple thousand dollars depending on what’s recommended.

Only after you finish everything the SAP recommends can you take a return-to-duty test. That test must be directly observed, and you need a verified negative before going back to safety-sensitive work. The SAP then sets the follow-up plan: at least six unannounced tests over the first 12 months, potentially extending for up to 48 more months. Every follow-up test is directly observed as well.⁸

Your Rights When a Test Comes Back Positive

The Medical Review Officer is a licensed physician who acts as an independent check between the lab and the employer. When a lab reports a confirmed positive, the MRO first reviews the entire chain of custody for procedural errors. A broken chain of custody or a documentation flaw can invalidate the result.

If the paperwork holds, the MRO contacts you for a private interview. This is your chance to offer a legitimate medical explanation, most commonly a valid prescription for a medication that produced the positive result. If your documentation is convincing, the MRO can change the result to negative. Without a legitimate explanation, the MRO verifies the positive and reports it to the employer.

You also have a right to test the split specimen. When the MRO notifies you of a verified positive (or a refusal based on an adulterated or substituted specimen), you have 72 hours from that notification to request that the split be sent to a different HHS-certified laboratory for independent analysis.¹⁵ If the second lab fails to confirm the original result, the MRO cancels the test. You do not have to pay upfront, though the employer may seek reimbursement afterward. Reversals happen, but they are uncommon because the confirmatory testing on the primary bottle is already highly accurate.

Medical Marijuana and CBD

State legalization is irrelevant to DOT testing. Marijuana remains a Schedule I substance for DOT purposes, and using it while employed in a safety-sensitive transportation role is a federal violation regardless of whether your state has legalized medical or recreational use.¹⁶ A December 2025 executive order directed the Department of Justice to begin rescheduling marijuana to Schedule III, but as of early 2026 the DOT’s position has not changed and the testing rules are unchanged. A state-issued medical marijuana card is not a defense to a positive result.

CBD is a separate trap. The DOT tests for THC metabolites, not CBD itself. Many CBD products contain more THC than their labels claim, and the FDA does not certify THC levels in CBD products. If a CBD product causes you to test positive for THC, that is not a legitimate medical explanation, and the MRO will verify the result as positive. The DOT tells safety-sensitive employees to “exercise caution” with CBD, which in plain terms puts the risk on you.¹⁷

The FMCSA Clearinghouse Follows You

The FMCSA Clearinghouse is a national database that tracks drug and alcohol violations for CDL holders. It closed the old loophole that let a driver fail a test with one carrier and start clean at the next.

Employers must run two types of queries. A full query, which shows the details of any recorded violation, is required before hiring any CDL driver. A limited query, which only tells the employer whether a violation exists, must be run at least once a year on every current CDL driver.¹⁸ Both cost $1.25 per query as of 2026. If a limited query returns a hit, the employer follows up with a full query and pays only once for the pair.

Full queries require your specific electronic consent through the Clearinghouse system, so you need a Clearinghouse account. If you refuse consent for a full query, the employer must pull you from safety-sensitive work until the query is completed.¹⁹ Limited queries use a general consent obtained outside the system, and that consent can cover more than one year.

Employers report violations to the Clearinghouse within three business days of learning about them.²⁰ Reportable events include an alcohol confirmation test at 0.04 or higher, a refusal to test, and actual knowledge of drug or alcohol use as defined by the regulations. MROs separately report verified positive drug results and refusals that require their determination. A violation stays visible to prospective employers until the return-to-duty process is complete, which is what makes a single failed test capable of shutting down a driving career for as long as it takes to work through the SAP program.

1
eCFR. 49 CFR Part 382 – Controlled Substances and Alcohol Use and Testing
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eCFR. 49 CFR Part 382 – Controlled Substances and Alcohol Use and Testing – Section 382.305
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eCFR. 49 CFR 382.301 – Pre-Employment Testing
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eCFR. 49 CFR 382.305 – Random Testing
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U.S. Department of Transportation. Random Testing Rates
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eCFR. 49 CFR 382.303 – Post-Accident Testing
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eCFR. 49 CFR 382.107 – Definitions
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U.S. Department of Transportation. 49 CFR Part 40 Section 40.307
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eCFR. 49 CFR Part 40 – Procedures for Transportation Workplace Drug and Alcohol Testing Programs – Section 40.82
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U.S. Department of Transportation. DOT Rule 49 CFR Part 40 Section 40.210
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GovInfo. 49 CFR 382.505 – Other Alcohol-Related Conduct
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eCFR. 49 CFR 40.191 – Refusal to Take a DOT Drug Test
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U.S. Department of Transportation. 49 CFR Part 40 Section 40.67
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eCFR. 49 CFR 382.605 – Referral, Evaluation, and Treatment
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eCFR. 49 CFR 40.153 – MRO Notification of Split Specimen Rights
16
Drug and Alcohol Clearinghouse. In Case You Missed It: Updates from ODAPC
17
U.S. Department of Transportation. DOT CBD Notice
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Federal Motor Carrier Safety Administration. Query Plans
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Federal Motor Carrier Safety Administration. Queries and Consent Requests
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FMCSA Clearinghouse. How to Report a Violation: Employers