FMCSA drug and alcohol testing rules generally cover drivers operating commercial vehicles in commerce that require a CDL or Commercial Learner's Permit (CLP). Holding a CDL without doing covered work does not, by itself, put you in an employer's testing program. See 49 CFR 382.103.
For CDL students, the permit matters. A school test given before a student holds a CLP or CDL is not a DOT test under these rules. Covered training operations after the student holds the credential can fall under Part 382. Ask the school which type of test it requires and who manages compliance. FMCSA explains the student-driver distinction.
When are you tested?
For covered drivers, the federal program includes:
- Pre-employment: Generally, the employer must receive an MRO-verified negative drug-test result before allowing covered driving. Part 382 has limited exceptions; do not assume a prior employer's test automatically qualifies.
- Random: Unannounced testing continues during covered employment.
- Reasonable suspicion: Testing must be based on the required observations by a trained supervisor or company official.
- Post-accident: Testing depends on the conditions below.
- Return-to-duty and follow-up: These apply after a qualifying violation when a driver seeks to resume safety-sensitive work.
FMCSA's testing overview describes each category.
Not every crash requires a federal test
Under 49 CFR 382.303, the rule covers an occurrence involving a CMV operating on a public road in commerce:
| Accident outcome | Federal testing condition |
|---|---|
| A human fatality | Test the surviving driver who was performing safety-sensitive functions with respect to the vehicle, whether or not cited. |
| Bodily injury requiring immediate medical treatment away from the scene | Test if the CMV driver receives a moving-traffic citation arising from the accident within the applicable window. |
| Disabling damage requiring any involved motor vehicle to be transported away | The same citation condition applies. |
For the injury and disabling-damage categories, the citation window is 8 hours for alcohol and 32 hours for drugs, measured from the accident. Required tests must occur as soon as practicable. Employers must document an alcohol-testing delay beyond two hours, stop alcohol-test attempts after eight hours, and stop drug-test attempts after 32 hours, documenting why testing was not completed.
Remain available for required testing. The rule does not require delaying necessary medical attention or prevent leaving to obtain emergency care or assistance.
What does the DOT test for?
The current federal urine-testing panel covers marijuana metabolites, cocaine metabolites, specified opioids, amphetamines and PCP. The opioid category includes specified substances; it does not mean every opioid is included.
Arizona marijuana permissions do not excuse a positive DOT test. In its May 2026 marijuana Q&A, DOT states that state medical-marijuana cards, recommendations and dispensary records do not provide a legitimate medical explanation for a marijuana-positive result, even after the rescheduling of qualifying products. DOT also warns that CBD products can contain THC and CBD use is not an acceptable explanation for a confirmed marijuana positive.
What happens during a urine collection?
Under DOT's urine collection procedures, expect identity checks, instructions about outer clothing and pockets, hand hygiene, specimen collection, and custody-and-control paperwork. The collector checks the sample, divides it between primary and split-specimen bottles, and seals them in your presence. You initial the bottle seals.
Ordinary collections generally allow privacy. Certain circumstances require direct observation, including return-to-duty and follow-up drug tests. A DOT physical's medical urinalysis is a separate process.
A Medical Review Officer (MRO) reviews laboratory findings. For results subject to medical explanation, the MRO gives you an opportunity to provide supporting information, such as a legally valid prescription. The MRO determines whether that explanation meets the rule; a prescription does not itself establish fitness to drive. See DOT's verification rule.
Violations, the Clearinghouse and returning to work
A verified positive and a refusal are different violations. Either can bar safety-sensitive work and require the federal return-to-duty process with a qualified Substance Abuse Professional (SAP). Taking another test on your own does not complete that process. Follow-up testing includes at least six tests in the first 12 months of safety-sensitive duty and can extend through 60 months of safety-sensitive duty. FMCSA explains these requirements.
The FMCSA Drug & Alcohol Clearinghouse records qualifying FMCSA program violations; it is not a database of every DOT test across all transportation industries. States must deny specified CDL/CLP transactions for prohibited drivers and remove commercial privileges through the downgrade process unless the prohibition is resolved in time. Completing return-to-duty and restoring state privileges are related steps; verify both before driving. See FMCSA's state licensing requirements.
