Driver Conduct Rules: Alcohol, Drugs, Fatigue, Passengers and Pre-Trip Checks
A CDL driver may not use alcohol within 4 hours before going on duty (49 CFR 392.5). A driver may not drive with an alcohol concentration of 0.04 or more (382.201). Drivers may not drive while too tired or sick to do it safely (392.3). A driver may not carry a passenger without the carrier's written approval, except for people the carrier assigns, emergency aid and a livestock attendant (392.60).
Facts checked October 21, 2026
Key Points
- No driver may use alcohol, or be under the influence of alcohol, within 4 hours before going on duty or operating a commercial motor vehicle. No driver may use alcohol while on duty or in physical control of the vehicle (49 CFR 392.5(a) and 382.207)
- A driver may not report for or stay on duty with an alcohol concentration of 0.04 or greater (49 CFR 382.201). After a crash that needs an alcohol test, a driver may not use alcohol for 8 hours or until tested, whichever comes first (382.209)
- A driver may not be on duty or drive while possessing wine of 0.5 percent alcohol or more, beer or distilled spirits. A shipment that is manifested and transported is not covered (49 CFR 392.5(a)(3))
- A driver who breaks the alcohol rule is placed out of service for 24 hours. The driver must tell the employer within 24 hours and the state licensing official within 30 days (49 CFR 392.5(c) and (d))
- A driver on duty may not possess, use or be under the influence of a Schedule I substance, an amphetamine or a narcotic. The same goes for any other substance that makes the driver unable to drive safely (49 CFR 392.4(a)). A substance given by a licensed medical practitioner who advised that it will not affect safe driving is allowed. This does not cover Schedule I substances (392.4(c) and 382.213)
- No driver may drive when fatigue, illness or any other cause makes it unsafe to begin or continue. No carrier may require or permit it. The one exception is a grave emergency (49 CFR 392.3)
- No driver may carry anyone on a commercial vehicle, other than a bus, without the carrier's written approval. Three cases need no approval: people the carrier assigned, people helped in an accident or emergency, and a livestock attendant (49 CFR 392.60)
- Before driving, the driver must be satisfied that these parts work: service brakes, parking brake, steering, lights, tires, horn, wipers, mirrors, coupling devices, wheels and rims, and emergency equipment (49 CFR 392.7)
Driver conduct limits for commercial motor vehicle drivers
| Item | What the rule says | Where | |
|---|---|---|---|
| Alcohol before duty | No use within 4 hours before going on duty or operating a commercial motor vehicle | 392.5(a)(1), 382.207 | |
| Alcohol concentration on duty | 0.04 or greater is prohibited. Any measured concentration or detected alcohol while on duty or in control of the vehicle is also prohibited | 382.201, 392.5(a)(2) | |
| Alcohol after a crash that needs a test | No use for 8 hours, or until the alcohol test is done, whichever is first | 382.209 | |
| Alcohol out-of-service period | 24 hours, starting when the order is issued | 392.5(c) | |
| Report an alcohol out-of-service order | To the employer within 24 hours, and to the state licensing official within 30 days | 392.5(d) | |
| Petition to review the order | In writing within 10 days of issue | 392.5(e) | |
| Drugs and substances | No possession, use or influence of Schedule I substances, amphetamines, narcotics or any substance that makes the driver unable to drive safely. A practitioner's advice allows non-Schedule I substances | 392.4, 382.213 | |
| Fatigue and illness | No driving when ability or alertness is impaired so that it is unsafe. A grave emergency lets the driver continue to the nearest place where the hazard is removed | 392.3 | |
| Passengers | Written approval from the carrier naming the person, the start and end points and an expiry date. No approval for assigned employees or persons, emergency aid, or a livestock attendant | 392.60 | |
| Cargo check | Check within the first 50 miles, then again at a change of duty status, after 3 hours of driving or 150 miles, whichever comes first | 392.9(b) |
How long before driving can a trucker drink alcohol?
A driver may not use alcohol within 4 hours before going on duty or operating a commercial motor vehicle (49 CFR 392.5(a)(1) and 382.207). A driver may not use alcohol at all while on duty, or while operating or in physical control of the vehicle (392.5(a)(2) and 382.205). A carrier may not require or permit a driver to break these rules. It also may not let a driver work if the driver's look or conduct shows alcohol use in the last 4 hours (392.5(b)). After a crash that needs an alcohol test, the driver may not drink for 8 hours, or until tested, whichever comes first (382.209). A driver who breaks the rule is put out of service at once for 24 hours.
What is the alcohol limit for a CDL driver?
In a commercial motor vehicle, the federal limit is 0.04. A driver may not report for or stay on duty with an alcohol concentration of 0.04 or greater (49 CFR 382.201). A conviction for driving under the influence of alcohol under state law disqualifies a CDL holder for 1 year for a first offense. This holds whether the driver was in a truck or in a personal vehicle. It is 3 years if the driver was hauling placarded hazardous materials, and life for a second offense (49 CFR 383.51(b)). Having 0.04 or more while operating a commercial motor vehicle is its own disqualifying offense. See the CDL disqualification page for the full table.
Can truck drivers take prescription medication?
Often yes, but not every drug. A driver on duty may not possess, use or be under the influence of a Schedule I substance, an amphetamine or a narcotic. The same goes for any other substance that makes the driver unable to drive safely (49 CFR 392.4(a)). The rule excepts a substance given by or under the instructions of a licensed medical practitioner. The practitioner must have advised the driver that it will not affect safe driving. That exception does not cover Schedule I substances (392.4(c)). The testing rule says a driver may use a non-Schedule I drug if a practitioner has said it will not adversely affect the ability to drive. The practitioner must know the driver's medical history (382.213(b)). An employer may require a driver to tell it about any therapeutic drug use (382.213(d)). A driver should ask the practitioner about the specific drug, and tell the practitioner that the job is driving a truck.
Can a truck driver drive when tired or sick?
No, if the tiredness or illness makes it unsafe. A driver may not operate a commercial motor vehicle when fatigue, illness or any other cause makes it unsafe to begin or continue (49 CFR 392.3). That covers a driver whose ability or alertness is impaired, or likely to become impaired. A carrier may not require or permit it either. The one exception is a grave emergency. That is where stopping would add to the hazard for the people on board or other road users. In that case the driver may continue to the nearest place where the hazard is removed. This rule stands on its own. A driver can be inside the hours of service limits and still break it.
Can truck drivers have passengers?
Only with the motor carrier's written approval, or in three cases that need none (49 CFR 392.60). The approval must name the person, the points where the ride starts and ends, and the date it expires. No written approval is needed for employees or other persons the carrier assigned to the vehicle. It is also not needed for anyone helped in an accident or other emergency, or for an attendant looking after livestock. The rule does not apply to buses. It also does not apply to a farmer who runs his or her own commercial vehicle to carry farm products or farm supplies. The rule sets no number of passengers. The limit is the carrier's approval. Many carriers have their own policy, so ask yours.
What must a driver check before every trip?
Before driving, the driver must be satisfied that these parts are in good working order. They are the service brakes including the trailer brake connections, the parking brake, steering, lights and reflectors, tires, horn, wipers, mirrors, coupling devices, wheels and rims, and emergency equipment (49 CFR 392.7(a)). The driver must also be satisfied that the emergency equipment required by 393.95 is in place and ready (392.8). Cargo comes next. The driver must make sure it is properly distributed and secured before driving. The driver must check it within the first 50 miles. Then the driver must check it again whenever duty status changes, after 3 hours of driving or after 150 miles, whichever comes first (392.9). A sealed vehicle, or one loaded so that inspection is impractical, is excepted.
What must a driver do in snow, ice, fog or rain?
Use extreme caution when snow, ice, sleet, fog, mist, rain, dust or smoke affect visibility or traction, and slow down (49 CFR 392.14). If conditions become dangerous enough, stop driving and do not start again until the vehicle can be driven safely. A carrier may not schedule a run that would need the vehicle to go faster than the speed limits where it travels. It may not require or permit one either (392.6). The driver must also follow the laws of the place where the vehicle is being operated. If a federal rule sets a higher standard of care, the federal rule applies (392.2).
Related Free Tools
Hours of Service (HOS) Tracker
Full 49 CFR Part 395 tracking. It covers the daily log, 14-hour window, 30-minute break, and the real 60/70-hour weekly rule with 34-hour restart detection.
Drug & Alcohol Testing Tracker
Track DOT-required random testing compliance. FMCSA minimums: 50% drug, 10% alcohol.
Driver Hiring and Onboarding Checklist
Every step a motor carrier takes to hire a CDL driver, in order, with the deadline and the federal rule for each one.
Pre-Trip / Post-Trip DVIR Checklist
A 49 CFR 396.11 compliant Driver Vehicle Inspection Report with defect tracking.
Frequently Asked Questions
What is the alcohol limit for a CDL driver?+
In a commercial motor vehicle it is 0.04. A driver may not report for or stay on duty with an alcohol concentration of 0.04 or greater (49 CFR 382.201). No alcohol at all is allowed within 4 hours before duty or while on duty (49 CFR 392.5).
What is the CDL alcohol limit in a personal vehicle?+
The state's own drunk driving law applies in a personal vehicle. A conviction for driving under the influence under state law also disqualifies a CDL holder from driving a commercial motor vehicle. It is 1 year for a first offense, even in a personal vehicle (49 CFR 383.51(b), Table 1).
How long after drinking can a truck driver drive?+
A driver may not use alcohol within 4 hours before going on duty or operating a commercial motor vehicle (49 CFR 392.5(a)(1) and 382.207). Four hours is a minimum. The 0.04 limit still applies, and a carrier can set a stricter policy.
Can a truck driver have alcohol in the truck?+
No, not while on duty or driving. A driver may not possess wine of 0.5 percent alcohol or more, beer or distilled spirits while on duty or operating a commercial vehicle. Alcohol that is manifested and transported as part of a shipment is not covered (49 CFR 392.5(a)(3)).
What happens if a driver violates the alcohol rule?+
The driver is placed out of service for 24 hours. The driver must tell the employer within 24 hours and the state licensing official within 30 days (49 CFR 392.5(c) and (d)). The driver may petition for review within 10 days.
Can truck drivers take prescription medication?+
Often yes. A substance given by a licensed medical practitioner who advised that it will not affect safe driving is allowed. This does not cover Schedule I substances (49 CFR 392.4(c) and 382.213(b)). Ask the practitioner about the specific drug and tell them you drive a truck.
Can truck drivers have passengers?+
Only with the carrier's written approval naming the person, the start and end points and an expiry date. No approval is needed for people the carrier assigned, for emergency aid, or for a livestock attendant (49 CFR 392.60).
How many passengers can a truck driver have?+
The federal rule sets no number. It requires the carrier's written approval for each person, with three exceptions (49 CFR 392.60). The carrier's policy and the vehicle's seats set the practical limit.
Can a driver drive when tired?+
Not when fatigue, illness or any other cause makes it unsafe to begin or continue. A carrier may not require or permit it either. A grave emergency is the only exception (49 CFR 392.3).
How often must a driver check cargo?+
Within the first 50 miles of a trip. Then again at each change of duty status, after 3 hours of driving or after 150 miles, whichever comes first (49 CFR 392.9(b)).
More federal trucking rules
- Hours of Service Rules for Truck Drivers
- ELD Mandate: Who Needs an ELD
- DOT Roadside Inspection Levels Explained
- DOT Drug and Alcohol Testing Rules
- Driver Qualification File Requirements
- DVIR and Vehicle Maintenance Rules
- New Entrant Safety Audit Requirements
- Hours of Service Exceptions and Exemptions
- Motor Carrier Insurance Requirements
- CDL Classes, Endorsements and ELDT Training
- DOT Physical and Medical Card Requirements
- Drug and Alcohol Clearinghouse Requirements
- Cargo Securement Rules for Trucks
- Hazmat Basics for Truck Drivers and Carriers
- USDOT Number and Biennial Update Requirements
- Safety Ratings, Compliance Reviews and DataQs
- Federal Truck Size and Weight Limits
- California Clean Truck Check (HD I/M)
- Truth-in-Leasing Rules for Owner-Operators
- Form 2290 Heavy Highway Vehicle Use Tax
- Truck Driver Phone, Texting and Seat Belt Rules
- Railroad Crossing Rules for Truck Drivers
- Truck Emergency Equipment and Warning Triangle Rules
- Truck Windshield, Dash Cam and Mirror Rules
- CDL Disqualification: Major and Serious Offenses
- Truck Tire Rules: Tread Depth, Retreads and Pressure
- Trailer Reflective Tape (Conspicuity) Rules
- Truck Brake Rules: Pushrod Stroke, Lining Thickness and ABS
- English Language Proficiency for Truck Drivers: The 391.11(b)(2) Rule
- Weigh Station Rules: Who Must Stop and What Happens If You Skip
- Truck Lighting Rules: Required Lamps and Reflectors (49 CFR 393)
- Driver Road Test Rules: The Company Road Test and Certificate (49 CFR 391.31)
Related terms and pages
Sources
- 49 CFR 392.3, Ill or fatigued operator (eCFR)
- 49 CFR 392.4, Drugs and other substances (eCFR)
- 49 CFR 392.5, Alcohol prohibition (eCFR)
- 49 CFR 392.7, Equipment, inspection and use (eCFR)
- 49 CFR 392.9, Inspection of cargo, cargo securement devices and systems (eCFR)
- 49 CFR 392.14, Hazardous conditions; extreme caution (eCFR)
- 49 CFR 392.60, Unauthorized persons not to be transported (eCFR)
- 49 CFR 382.201 to 382.215, Prohibitions (eCFR)
- 49 CFR 383.51, Disqualification of drivers (eCFR)
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This is a plain-language summary for reference, not legal advice. Check the official rule text before you rely on any detail. Ask a compliance professional about your own operation.