DOT Drug and Alcohol Testing for Commercial Drivers: What You Need to Know

March 1, 2023

The Department of Transportation (DOT) requires drug and alcohol testing of safety-sensitive employees to maintain the safety of others who may also be traveling. This requirement was enacted in 1991, and the drug screening rules are listed within Title 47 CFR Part 40, commonly referred to as Part 40. 

An office publishes the rules within the DOT called the Office of Drug & Alcohol Policy Compliance (ODAPC). This article covers information about DOT drug and alcohol testing for commercial drivers.

Who is required to get DOT drug and alcohol tests?

The DOT enforces drug and alcohol testing for individuals classified as ‘safety-sensitive’ employees. These include many positions, such as employees of the following organizations:

And finally, holders of a Commercial Driver’s License (CDL) who operate commercial motor vehicles. The FMCSA and the DOT require that all individuals that meet the following conditions be subject to DOT drug and alcohol testing.

When are drivers tested?

DOT drug and alcohol testing regulations require that drivers are tested at specific times or under particular conditions.


A new driver must have a negative result before an employer can allow them to operate a CMV on a public road. In addition, if the driver is removed from the random testing pool for over thirty days, he must also receive another pre-employment test. 


CDL drivers must be subject to random, unannounced testing when the driver is off-duty or immediately before or after duty. Once selected for random urinalysis, they must immediately report for testing. A delayed arrival may be reported as a refusal to test. 

When reasonably suspicious

If a DOT-trained supervisor suspects a driver is impaired, they may require a drug or alcohol screening. 


CDL drivers must be tested for drugs or alcohol after a fatal accident or after receiving a traffic citation resulting from an injury or vehicle-disabling accident. They must also complete these tests within the required window of time. For example, they must be tested for alcohol within 8 hours and drugs within 32 hours.


Drivers who have failed a urinalysis or have refused to take one must submit to a directly observed test after completing other steps in the return-to-duty process. If the driver passes, they are subject to unannounced follow-up testing at least six times in the first year of the return to duty.  

What substances are covered in a DOT drug test?

DOT drug tests require that drug testing laboratories screen for the following substances:

Any results that indicate using an illegal drug, an anti-seizure drug, or methadone will cause the driver to fail a test. Additionally, prescription drugs may be allowed so long as the prescribing doctor can write that the driver is safe for operating a commercial vehicle while taking the prescription. 

What happens if I have been selected for DOT drug and alcohol testing?

You must arrive at the collection site immediately if you have been notified to report for testing. The DOT requires a urinalysis completed by an approved drug testing laboratory. Other forms of drug or alcohol testing are unacceptable. 

If there are any problems with your test, you may be required to retest under direct observation. Leaving the site before a sample has been successfully collected is considered a ‘refusal’ to take the test. Once the sample is tested, the laboratory will submit a report to the medical review officer. If the results are positive, they must be reported to the employer and the drug and alcohol clearinghouse. However, your test results are confidential, and employers cannot share sensitive information with unauthorized individuals without your written consent. However, your test information may be released for legal proceedings, grievances, or administrative proceedings brought on by you or your behalf. 

What happens if I refuse to take or fail a DOT drug or alcohol test?

A refusal to test or a positive result requires that the employer immediately remove the driver from operating a CMV on public roadways. The employer must also provide a list of qualified substance abuse professionals (SAPs) that may commence the return-to-duty process required before returning to driving.

Unfortunately, the return-to-duty process is complex and can take months, during which time the driver is usually unemployed and unqualified for employment as a commercial driver. Employment decisions based on a failed drug or alcohol test are made solely by the employer. DOT regulations do not address or require any actions, such as termination. Additionally, a failed test will stay on your record even if you start working for a new employer.  

The FMCSA established the CDL Drug and Alcohol Clearinghouse, which includes information about violations of DOT’s drug and alcohol testing program for holders of CDLs. This Clearinghouse requires that FMCSA-regulated employers, medical review officers, substance abuse professionals, third-party administrators, and other service agents report information about violations. 

This Clearinghouse provides FMCSA and employers with information to identify drivers prohibited from operating a CMV. 

Where can I find additional guidance and resources about DOT drug and alcohol testing? 

The USDOT and FMCSA have additional guidance and resources online for employers and drivers. These materials may be referenced at any time to provide more information about how to comply with the regulations required by the DOT. 

Periodically referencing these materials can help you stay up-to-date on current compliance requirements.

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