The safety of America’s highways depends on the professionalism and reliability of commercial drivers. An important part of maintaining that safety is ensuring drivers are drug- and alcohol-free.
For fleet owners and operators, understanding and complying with the DOT’s drug and alcohol testing requirements isn’t optional. Here’s a quick breakdown of what you need to know to protect your business, avoid fines, and keep your team rolling safely.
Who Is Subject to DOT Drug & Alcohol Testing?
Any driver operating a commercial motor vehicle (CMV) that requires a CDL (Class A, B, or C with endorsements) and operates in interstate commerce is subject to federal drug and alcohol testing rules under 49 CFR Part 382.
This applies to:
- For-hire and private carriers
- Owner-operators
- Contracted FedEx fleet drivers
- Bus and motorcoach operators
Even if your drivers rarely drive or operate part-time, if they hold a CDL and are assigned to a position that may require driving, they are covered.
When Do You Have to Test?
DOT-mandated drug and alcohol testing isn’t just a one-time thing; it’s an ongoing process. Fleet owners must ensure drivers are tested under the following scenarios:
- Pre-employment – Before a new hire can drive a CMV, they must pass a drug test. (Alcohol testing is not required at this stage, but can be conducted.)
- Random testing – Carriers must enroll drivers in a random testing pool. For 2025, the DOT minimum testing rates are:
- 50% of drivers annually for drugs
- 10% of drivers annually for alcohol
- Post-accident – Required when a driver is involved in certain types of accidents, especially those involving fatalities or citations with injuries/towing.
- Reasonable suspicion – When a supervisor trained in signs of impairment observes behavior that suggests drug or alcohol use.
- Return-to-duty – After a positive test or policy violation, a driver must complete the Substance Abuse Professional (SAP) process and pass a test before returning to safety-sensitive duties.
- Follow-up – An SAP will require follow-up testing after the employee returns to duty. These are unannounced and can last up to 5 years.
What Drugs Are Tested?
DOT-regulated drug tests are conducted via urine samples and screen for the following five substances:
- Marijuana (THC)
- Cocaine
- Amphetamines (including methamphetamine)
- Opiates (including heroin, codeine, morphine)
- Phencyclidine (PCP)
Note: CBD products are not a valid excuse for a positive THC test. Drivers are responsible for what’s in their system.
Alcohol Testing – What’s the Limit?
Alcohol tests can be performed via breath or saliva testing. A result of 0.02 to 0.039 BAC requires the driver to be removed from duty for at least 24 hours. A BAC of 0.04 or higher is considered a DOT violation and triggers the return-to-duty process.
Common Mistakes That Trigger Violations
Even experienced fleet owners make compliance errors. Watch out for:
- Not conducting a pre-employment test before the first drive
- No random testing program or testing too few drivers
- Missing required post-accident tests
- Incomplete or missing supervisor’s reasonable suspicion training
- Not checking the FMCSA Clearinghouse before hiring
What is the FMCSA Clearinghouse?
As of January 2020, all DOT-regulated carriers must query the FMCSA Clearinghouse when hiring new CDL drivers, and annually for current drivers. This system tracks violations and ensures that drivers with unresolved drug/alcohol issues aren’t slipping through the cracks.
Final Thoughts
DOT drug and alcohol testing rules aren’t just legal requirements—they’re essential safety measures. Staying compliant protects your drivers, your CSA scores, your insurance premiums, and the public.
Whether you’re running a single truck or managing a fleet of 100 or more, staying on top of these requirements should be part of your core safety strategy.
If you’re unsure about your current compliance status or want to simplify your safety program, reach out for a free demo of Linehaul Central’s safety tools.
