Hours of Service, Licensing, and Driver Fitness
The rules in this chapter are the ones that end careers when they are broken. Hours-of-service limits exist because fatigue impairs a driver much like alcohol does, the alcohol and drug rules for CDL holders are twice as strict as those for other drivers, and a short list of major offenses can disqualify a commercial license for a year or for life. This chapter covers the 11-hour, 14-hour, 30-minute, and 60/70-hour limits and the 34-hour restart, electronic logging, disqualifying offenses, alcohol and controlled substances, medical certification, distracted driving, and the fatigue and illness rules that require a driver to stop.
Hours of Service Limits
A property-carrying driver may drive up to 11 hours after taking 10 consecutive hours off duty, and all of that driving must be completed within a 14-consecutive-hour window that begins the moment the driver comes on duty. The 14-hour window does not stop for meals, fuel stops, or off-duty breaks, so a driver who comes on duty at 6:00 a.m. may not drive after 8:00 p.m. regardless of how many hours were spent waiting at a dock. Within that window, a driver may not drive after 8 cumulative hours of driving time without at least a 30-minute interruption of driving, which may be satisfied by any 30 consecutive minutes of off-duty, sleeper berth, or on-duty not driving time. On top of the daily limits are weekly limits: 60 hours on duty in any 7 consecutive days for carriers that do not operate every day of the week, and 70 hours in any 8 consecutive days for carriers that do. Those weekly totals may be reset by taking at least 34 consecutive hours off duty. Two flexibilities are worth knowing. The sleeper berth provision lets a driver split the required off-duty time into two qualifying periods, and the adverse driving conditions exception allows up to two additional hours of driving time and extends the 14-hour window by the same two hours when conditions could not have been known before dispatch. Neither one removes the duty to record hours accurately.
Logbooks and Electronic Logging Devices
Records of duty status document compliance with the hours rules, and most drivers now keep them on an electronic logging device that connects to the engine and records driving time automatically, removing the possibility of understating hours behind the wheel. A driver must still enter the non-driving duty statuses, annotate records, certify each day, and produce the records to an enforcement officer on request, which requires knowing how to transfer the data or display it on the device. Drivers must also keep supporting documents such as bills of lading, fuel receipts, and dispatch records, since these are used to verify the electronic record. There are limited exceptions to the ELD requirement, including drivers who use paper records for a small number of days in a month and drivers operating certain older vehicles. The short-haul exception excuses some drivers from keeping records of duty status entirely when they operate within a limited air-mile radius of the normal work reporting location and return within a set number of hours each day, but a driver who exceeds those limits on any day must complete a record for that day. Falsifying a record of duty status is a serious violation for both the driver and the carrier, and it is one of the first things investigators examine after a fatigue-related crash.
Alcohol, Drugs, and Disqualification
The legal alcohol limit for operating a commercial vehicle is 0.04 blood alcohol concentration, half the limit that applies to most other drivers, and any detectable alcohol while on duty places a driver out of service for 24 hours. Drivers are prohibited from using alcohol within four hours of going on duty, from possessing alcohol on the vehicle except as part of a manifested shipment, and from using controlled substances except when prescribed by a physician who has advised that the substance does not impair the driver's ability. Refusing a required test carries exactly the same penalty as testing positive. Disqualifying offenses fall into two groups. Major offenses, including driving under the influence, refusing a test, leaving the scene of a crash, using a commercial vehicle to commit a felony, and driving a commercial vehicle with a suspended or revoked CDL, bring at least a one-year disqualification, three years if the driver was hauling placarded hazardous materials, and a lifetime disqualification for a second offense. Serious traffic violations, which include excessive speeding of 15 mph or more over the limit, reckless driving, improper or erratic lane changes, following too closely, texting, using a hand-held phone, and driving a commercial vehicle without a valid CDL, bring a 60-day disqualification for two convictions within three years and 120 days for three. Railroad crossing violations and violations of an out-of-service order carry their own escalating penalties.
Medical Certification and Driver Fitness
An interstate commercial driver must be medically qualified and hold a valid medical examiner's certificate issued by a certified medical examiner. A standard certificate is valid for a maximum of 24 months, and the examiner may issue a shorter certificate, often one year, when a condition such as controlled high blood pressure requires closer monitoring. Certain conditions disqualify a driver from interstate operation unless an exemption has been granted, including insulin-treated diabetes without the required exemption, epilepsy or other conditions likely to cause loss of consciousness, vision or hearing below the required standards, and current use of certain controlled substances. Vision standards require at least 20/40 acuity in each eye with or without correction, at least 70 degrees of field of vision in the horizontal meridian in each eye, and the ability to distinguish standard traffic signal colors. A driver must not operate a commercial vehicle while ability or alertness is impaired through fatigue, illness, or any other cause. That rule has no exception for available driving hours, delivery deadlines, or a driver's confidence that they can push through. If you notice heavy eyelids, drifting in the lane, missed exits, or difficulty remembering the last few miles, the regulation requires you to stop driving. Prescription and over-the-counter medications deserve the same caution, since many cause drowsiness that is dangerous in a heavy vehicle.
Distracted Driving and Everyday Compliance
Federal rules prohibit texting and the use of a hand-held mobile telephone while driving a commercial motor vehicle. A driver may use a hands-free device if it can be operated with no more than a single push of a button and is positioned so it can be reached while properly restrained by the seat belt. Reaching for a phone in a way that requires leaving the seated driving position, holding a phone to the ear, and dialing more than one button all violate the rule, and so does texting while temporarily stopped in traffic. The penalties are substantial civil fines for the driver and much larger fines for an employer who allows or requires the behavior, plus disqualification of 60 days for two convictions in three years and 120 days for three. Seat belts are required whenever the vehicle is operated, with no exception for experience, short trips, or road type, and being ejected from the cab is a leading cause of death in truck crashes. Beyond these specific rules, everyday compliance means knowing that a CDL holder is held to a higher standard than other drivers: convictions in a personal vehicle can affect the commercial license, an out-of-service order must be obeyed, and violations follow the driver rather than the truck. Building safe habits is not only how you pass the test, it is how you keep the license you worked for.
Last updated: July 2026