DOT-regulated employers must test employees who perform safety-sensitive work for drugs and alcohol, using the procedures in 49 CFR Part 40 and the rules of their DOT agency. This page summarizes the essentials, using the FMCSA rules for CDL drivers (49 CFR Part 382) as the example. Other DOT agencies follow the same Part 40 procedures with their own "who and when" rules.

When employees are tested

Test	When	Rule
Pre-employment	Before a driver first performs safety-sensitive functions. A verified negative drug result is required; alcohol testing is optional.	49 CFR 382.301
Random	Unannounced, spread through the year, at or above the DOT minimum rates.	49 CFR 382.305
Post-accident	After a qualifying accident: alcohol within 8 hours (ideally 2), drugs within 32 hours.	49 CFR 382.303
Reasonable suspicion	When a trained supervisor observes signs of drug or alcohol use and documents them.	49 CFR 382.307
Return-to-duty	After a violation, once the SAP says the employee is ready. Drug tests are directly observed.	49 CFR 382.309
Follow-up	Unannounced, at least six in the first 12 months back, as set by the SAP.	49 CFR 40.307

What the tests check

• Drugs: the DOT test is a 5-panel test for marijuana, cocaine, amphetamines (including methamphetamine and MDMA), opioids (including codeine, morphine, heroin, hydrocodone, hydromorphone, oxycodone, and oxymorphone), and phencyclidine (PCP) (49 CFR 40.82). Laboratories may not test DOT specimens for anything else. DOT tests are urine tests; the 2023 Part 40 final rule also authorized oral fluid testing.
• Alcohol: a breath or saliva screening test, and a breath confirmation test if the screen is 0.02 or higher. A confirmed result of 0.04 or higher is a violation (49 CFR 382.201). A result of 0.02 to 0.039 is not a violation, but the driver must be removed from safety-sensitive functions for at least 24 hours (49 CFR 382.505).

Refusals

Refusing a test has the same consequences as a positive result. Refusals include not showing up (except for pre-employment tests), leaving the site before the test is complete, not cooperating, an adulterated or substituted specimen, and failing to provide enough urine or breath without a medical explanation (49 CFR 40.191, 49 CFR 40.261).

MRO review

A Medical Review Officer reviews every laboratory drug result before the employer sees it. For a non-negative result, the MRO interviews the employee and reports a positive only if there is no legitimate medical explanation. The employee may ask for the split specimen to be tested within 72 hours.

After a violation

An employee with a violation must be removed from safety-sensitive functions immediately and may return only after completing the return-to-duty process with a Substance Abuse Professional (SAP): evaluation, education or treatment, a negative return-to-duty test, and follow-up testing. For CDL drivers, violations and return-to-duty progress are reported to the FMCSA Clearinghouse.

What the employer must do

• Adopt a written policy and give drivers educational materials; train supervisors to recognize signs of drug and alcohol use (49 CFR 382.601, 49 CFR 382.603).
• Name a Designated Employer Representative (DER) to receive results and remove employees from duty.
• Check previous DOT employers' testing records and query the Clearinghouse before hiring (49 CFR 40.25, 49 CFR 382.701).
• Keep records for the required periods and submit the annual MIS report when asked (49 CFR 382.401, 49 CFR 382.403).

How Med-Stop helps

• Order a test: Create a test request.
• Find results: Find tests and results.
• Manage your own random testing program with the Med-Stop Random Selection Service: Random testing in Med-Stop.

Your company remains responsible for compliance even when Med-Stop provides these services. Med-Stop is not a consortium or C/TPA.

Common questions

• What are the types of DOT drug and alcohol tests?
• What is a pre-employment drug test?
• What is post-accident testing?
• What is reasonable suspicion testing?
• What is follow-up testing?
• What drugs are tested in the DOT drug test?
• Why has a urine drug test been requested?
• What is the breath alcohol test?
• What alcohol concentration is considered a violation?
• What happens if an employee refuses to test?
• What is a dilute specimen?
• What is an adulterated or substituted specimen?
• What is a Medical Review Officer (MRO)?
• What is the return-to-duty (RTD) process?
• What is a non-DOT test?
• How long must drug and alcohol records be retained?