600 Forest St. #101
Georgetown, Texas 78626

CDL Alcohol Limit

What is the legal alcohol limit while driving a commercial motor vehicle?

.04 is the legal limit according to the Federal Motor Carrier Safety Administration.

It is interesting that an amount above zero is allowed. Many companies may have stricter company policies than the federal laws though.

What are Safety Sensitive Functions?

A driver is performing Safety Sensitive Function when-

  • Waiting to be dispatched
  • Inspecting equipment
  • inspecting a Commercial Motor Vehicle (CMV)
  • Servicing a CMV
  • Conditioning a CMV
  • At the driving controls of a CMV
  • All time other than driving time in or upon any CMV except resting in a sleeper berth

4 Hours From Bottle to Throttle

The driver is not permitted to operate a commercial motor vehicle within 4 hours after consuming alcohol under the Pre-Duty Use provision in the code. This rule might be considered to be slightly lax since it still allows someone with alcohol in their system to drive a big rig.

There are varying degrees of intoxication. There are different ways to become intoxicated either by alcohol or drugs or a combination. The risk of injuring others with an 18 wheeler vs a car greatly increases the odds of serious injury. It makes sense that the alcohol limit would be less than .08.

No On-Duty Use

An employer who has actual knowledge that a driver is using alcohol while driving (performing safety sensitive functions) can allow the driver to continue.

But they can have drank 4 hours or more prior to performing safety sensitive functions as long as they are not above .04 alcohol concentration at the time of driving. Of course at no time are drivers allowed to use controlled substances except with a prescription. And certain prescription medication is not allowed while driving a CMV.

Post-Accident Testing

As soon as practicable after certain occurrence’s involving a commercial motor vehicle the employer must test for drugs and alcohol in the drivers system. The following are the situations that make a test required-

  • An accident involving the loss of human life
  • An alcohol test for a driver within 8 hours who receives a citation for a moving traffic violation and bodily injury to anyone requiring medical treatment away from the accident scene or
  • When one or more of the vehicles at the scene of the accident are disabled and required to be towed from the scene
  • A drug test within 32 hours of the accident if the driver received a citation for a moving violation and bodily injury requiring treatment away from the scene or a vehicle had to be towed from the incident

If no citation is issued the only instance where a driver must be tested is if there is loss of human life.

If an alcohol test is not administered within 2 hours the employer has to document it and maintain the record. If an alcohol test is not administered within 8 hours an explanation has to be recorded and submitted to FMCSA upon request.

If a drug test is not administered to the driver within 32 hours a record has to be made why it was not. The record shall be submitted to FMCSA upon request.

A driver must remain available for post-accident testing or be deemed as refusing the test. The driver is entitled to necessary medical care. A driver shall NOT use alcohol for 8 hours after an accident unless the driver has done the post-accident alcohol test.

The results of breath or blood tests by local law enforcement satisfy the FMCSA requirements.

Reasonable Suspicion Testing

The FMCSA under section 382.603 requires employers to require all who supervise drivers to get at least 60 minutes of training on alcohol “misuse” and at least an additional 60 minutes on controlled substance use. The training covers reasonable suspicion to believe the driver should be alcohol or drug tested. The training includes indicators of probable misuse of alcohol and controlled substance:

  • physical
  • behavioral
  • speech
  • performance indicators

Reasonable Suspicion Testing for Alcohol

In order to test for alcohol an employer must have “specific, contemporaneous, articulable observations concerning appearance, behavior, speech or body odors of the driver.”

Reasonable Suspicion Testing for Controlled Substances

Reasonable suspicion exists for controlled substance testing if based on “specific, contemporaneous, articulable observations concerning appearance, behavior, speech or body odors of the driver. The observations may include indications of the chronic and withdrawal effects of controlled substances.”

Who Can Observe Reasonable Suspicion?

A supervisor or company official who has trained in accordance of section 382.603 is qualified to determine if reasonable suspicion exists. A person who determines reasonable suspicion cannot conduct the alcohol test.

When is Alcohol Testing Required or Allowed?

The observations for reasonable suspicion testing are authorized only preceding, during or after the part of the work day when the driver is performing “safety sensitive functions.”

When is Alcohol Testing Done after Observed Reasonable Suspicion?

The alcohol testing should be done within 2 hours. If it is not within 2 hours the employer shall prepare and maintain the reason that the test was not done and keep it in a file. If the alcohol test is not done within 8 hours the employer shall document the reason and cease attempts at alcohol testing.

The federal regulations can be confusing. They state “no driver shall report for duty or remain on duty” during safety sensitive functions while under the influence or impaired by alcohol showing behavioral, speech, and performance signs of alcohol misuse. But once the driver’s alcohol test concentration is below .02 he or she may continue to perform “safety sensitive functions.” That would still seem to be “under the influence.”

In lieu of a test, if 24 hours has elapsed since reasonable suspicion was observed for alcohol, the driver can again perform safety sensitive functions.

FMCSA Clearinghouse DOT Reporting

In 2012 congress ordered the Director of Transportation to establish a reporting database for CMV operators who violated FMCSA regulations for drug and alcohol testing. Specifically-

  • Employers will be required to query the Clearinghouse for current and prospective employees’ drug and alcohol violations before permitting those employees to operate a commercial motor vehicle (CMV) on public roads.
  • Employers will be required to annually query the Clearinghouse for each driver they currently employ.
  • State Driver Licensing Agencies will be required to query the Clearinghouse whenever a CDL is issued, renewed, transferred, or upgraded.

A Medical Review Officer (MRV) must make a report to the Clearinghouse when they receive a-

  • Verified positive, adulterated or substituted controlled substance test result or
  • Changes to a verified drug test per 49 CFR Part 40 (Part 40 describes required procedures for conducting workplace drug and alcohol testing for the Federally regulated transportation industry)
  • Refusal to test in accordance with 49 CFR 40.191(a)(5), (7), and (11), (b), and (d)(2)

Employers must report the following information by the close of the third business day from the day the information was obtained-

  • Alcohol confirmation test with a concentration of .04 or higher
  • Negative return to duty test
  • Refusal to take an alcohol test pursuant to 49 CFR 40.261
  • Refusal per (Refusal subpart) 49 CFR 40.191(a)(1) through (4), (a)(6), (a)(8) through (11) or (d)(1)
  • For (a)(11) of a refusal the employer may only report admissions made to the specimen collector and report the driver has successfully completed all follow up tests as prescribed in the SAP report in accordance with section 40.307, 40.309, and 40.311

Employers must also report by the third business day of actual knowledge of-

  • On duty alcohol use
  • Pre duty alcohol use
  • Alcohol use following an incident
  • Controlled substance use

Evidence supporting each fact includes affidavits, photographs, video, audio recordings, employee statements, correspondence and other documentation and certificate of service or other evidence showing the employer provided the employee with all the information reported above.


With great weight comes great responsibility. Trucks are big and can be very lethal to pedestrians and other drivers. Regulation of drugs and alcohol is a necessary policy in the trucking industry. For questions or help look at our home page or personal injury page and contact us.