The Department of Transportation — also known as DOT — drug test is a federally regulated test required for employees with safety-sensitive jobs.

Employers must take care to fully comply with DOT drug testing regulations. Here’s what you need to know about DOT drug testing.

Why Does DOT Require Drug Tests?

DOT drug regulations and tests are designed to protect workers, their colleagues and the traveling public.

Employees in safety-sensitive jobs outlined in DOT regulations — those that have the potential to impact both their own safety and the safety of the public — must comply with drug testing. That’s because employees who operate or are responsible for vehicles or heavy machinery while under the influence pose a threat to the safety and life of themselves and the people around their vehicles/machinery. DOT drug tests allow employers to identify job applicants and employees unfit to work due to substance use.

Lives are saved by prohibiting drug and alcohol use and intoxication while on the job.

Who Has to Take DOT Drug Tests?

Anyone designated by DOT regulations as a safety-sensitive employee must adhere to DOT drug regulations and take part in drug testing. This includes:


  • Flight crews
  • Flight attendants
  • Flight instructors
  • Air traffic controllers
  • Aircraft dispatchers
  • Aircraft maintenance and preventative maintenance staff
  • Ground security coordinators
  • Aviation screeners

Commercial Motor Carriers

  • Commercial Drivers Licenses (CDL) holders who operate Commercial Motor Vehicles weighing 26,001 lbs. or more
  • Commercial Drivers Licenses (CDL) holders who operate a vehicle that carries 16 or more passengers (including the driver)
  • Commercial Drivers Licenses (CDL) holders who are required to display a DOT placard in the transit of hazardous materials


  • Crewmembers operating a commercial vessel


  • Operations
  • Maintenance
  • Emergency response personnel


  • Hours of Service Act personnel
  • Engine & train personnel
  • Signal service dispatcher
  • Train dispatchers


  • Vehicle operators
  • Controllers
  • Mechanics
  • Armed security

What Rules Does DOT Require Safety-Sensitive Employees Follow?

DOT outlines strict rules about the use of drugs and alcohol among safety-sensitive employees. Here’s what it prohibits these employees from doing:

  • Cannot use or possess alcohol or any illicit drug while assigned to perform safety-sensitive functions or actually performing safety-sensitive functions.
  • Cannot report for service, or remain on duty if they:
    • Are under the influence or impaired by alcohol
    • Have a blood alcohol concentration .04 or greater; (with a blood alcohol concentration of .02 to .039, some regulations do not permit employees to continue working until their next regularly scheduled duty period)
    • Have used any illicit drug
  • Cannot use alcohol within 4 hours (8 hours for flight crew members and
    flight attendants) of reporting for service or after receiving notice to report.
  • Cannot report for duty or remain on duty when using any controlled substance unless used pursuant to the instructions of an authorized medical practitioner.
  • Cannot refuse to submit to any test for alcohol or controlled substances.
  • Cannot refuse to submit to any test by adulterating or substituting their specimen.

When Can Employers Conduct a DOT Drug Test?

Employers complying with DOT regulations may perform a DOT drug test in several scenarios, ranging from pre-employment to post-accident. Some of these tests are preventative and are used to prevent employees under the influence from operating vehicles or heavy machinery. Others are reactionary, proving whether drugs or alcohol played a role in a workplace accident.

  • Pre-employment: All new hires must take a drug test before they can begin performing safety-sensitive functions.
  • Reasonable suspicion/cause: A drug test will be administered if a supervisor reasonably suspects — based on observation — that an employee is under the influence.
  • Random: A drug test will be given to an employee chosen by a true random selection process, where each employee has an equal chance of being selected for testing. The percentage of employees chosen for random testing varies by agency. You can view DOT’s random testing rates here.
  • Post-accident: Employees involved in work accidents that meet specific DOT agency criteria will be required to take a drug test to determine if they were under the influence at the time of the accident.
  • Return-to-duty: Employees that have broken DOT drug and alcohol rules must be re-tested before returning to work.
  • Follow-up: Follow-up testing is required for employees who have violated DOT regulations in the past.

What Drugs Does a DOT Drug Test Look For?

DOT drug tests use a 5-panel test that screens urine samples for the following substances:

  • Marijuana metabolites/THC
  • Cocaine metabolites
  • Amphetamines (including methamphetamine, MDMA)
  • Opiates (including codeine, heroin (6-AM), morphine)
  • Phencyclidine (PCP)

It’s important to note that the DOT does not make an exception for legal users of medical marijuana. All marijuana use — even when legal and prescribed by a doctor — is prohibited under DOT regulations.

What Happens During a DOT Drug Test?

Here’s how a DOT drug test works:

  1. A job candidate or employee will be notified that they must submit a drug test. This notification will tell them the reason for the test (whether it’s a pre-employment test, random, etc.).
  2. Upon notification, the individual must immediately report to the collection site to conduct the test.
  3. At the collection site, the individual will provide at least 45 ml of urine.
  4. The individual will then watch the specimen collector check the urine temperature, pour the sample into two bottles and then seal the bottles.
  5. The sample is sent to a lab for analysis.
  6. The lab then sends the results to a Medical Review Officer (MRO), who determines if — in the case of a positive result — there are any legitimate medical reasons for a positive result. They may review the individual’s medical records, schedule an interview with the patient, or request that they receive a physical exam to make a final determination.
  7. Results are shared with the employers.

Do You Have to Fire an Employee If They Fail a DOT Drug Test?

DOT does not regulate or make recommendations regarding termination or any other employment action. Every employer will responsible for determining the appropriate steps to take in the case of a failed drug test.

What Happens if Employers Aren’t DOT Compliant?

Employers who do not follow these regulations face financial and operational penalties. Exact penalties differ per agency, but fines range from hundreds to hundreds of thousands of dollars. In addition to financial penalties, employers failing to meet DOT compliance risk suspension or debarment.

DOT drug testing can be difficult, confusing and time-consuming. Need some help conducting tests and managing the drug testing process? Consider working with a DOT drug testing provider like JDP. You can learn more about how we help organizations in the transportation industry with drug tests and background screening here.