The Federal Motor Carrier Safety Regulations: A Reader's Map

The Federal Motor Carrier Safety Regulations decide who may operate a truck or bus in interstate commerce, for how long, in what condition and with what insurance behind it. Most readers meet them as citations: “49 CFR 395.3” on a roadside inspection report, “§ 396.11” in a lawsuit. This page maps who the rules reach, what the most-cited parts govern, how states carry the rules to trucks that never cross a state line, and where the text and the agency’s guidance live.

Who the rules reach

The rules apply to employers, employees and commercial motor vehicles that transport property or passengers in interstate commerce¹. Both halves of that sentence are defined terms, and both reach further than the plain words suggest.

Interstate commerce has three tests in 49 CFR 390.5T. It covers transport between a place in one state and a place outside it; transport between two places in the same state that passes through another state or country; and transport between two places in one state when the trip is part of a movement that begins or ends outside the state or the country². Under the third test, a truck that never leaves one state can still be in interstate commerce.

Commercial motor vehicle means a self-propelled or towed vehicle used on a highway in interstate commerce to carry passengers or property that meets any one of four tests²:

• a gross vehicle weight rating or gross combination weight rating, or an actual gross weight, of 10,001 pounds or more, whichever is greater;
• designed or used to carry more than 8 passengers, including the driver, for compensation;
• designed or used to carry more than 15 passengers, including the driver, when not carrying them for compensation;
• used to carry hazardous materials in a quantity that requires placards under the federal hazardous materials rules.

The weight test reaches well past tractor-trailers, to smaller trucks and to pickup-and-trailer combinations rated at 10,001 pounds or more.

Section 390.3T(f) lists exceptions, among them school bus operations, government transportation, fire and rescue vehicles in emergencies, and some 9-to-15-passenger vehicles not operated for direct compensation¹. Several exceptions keep particular sections in force, so the paragraph has to be read in full.

Two parts reach further. Part 383, the commercial driver’s license rules, applies to every person who operates a commercial motor vehicle in interstate or intrastate commerce¹, and it uses its own, heavier definition: generally 26,001 pounds or more, a vehicle designed to carry 16 or more people including the driver, or hazardous materials³. Part 382, drug and alcohol testing, follows the license and covers drivers subject to the CDL rules and their employers⁴.

The parts, one by one

Eleven parts cover the driver, the vehicle, the trip and the insurance. The right-hand column points to the sections a reader is likely to need first.

Two parts produce the numbers quoted most often: Part 395’s 11 hours of driving inside a 14-hour window, with caps of 60 hours in 7 days or 70 in 8⁶, and Part 387’s $750,000 floor for general freight⁷. The “accident” defined in 390.5T, an occurrence that results in a death, an injury treated away from the scene or a vehicle towed away with disabling damage², is what a carrier must log in its accident register.

The subchapter also covers operating authority (365), brokers (371), vehicle leasing (376) and record preservation (379)⁵. A liability question after a crash often draws on several parts at once; see liability in commercial vehicle collisions.

How states carry the rules to intrastate carriers

The FMCSRs bind interstate commerce. A truck that stays inside one state, on a trip that is not part of an interstate movement, answers to that state’s laws. Federal grant money links the two.

To qualify for Motor Carrier Safety Assistance Program funds, a state must adopt and enforce commercial vehicle safety laws compatible with the federal rules⁸. It reviews its laws each year and has no more than three years after a federal change takes effect to match it⁹. FMCSA can withhold funds from a state with an incompatible provision¹⁰.

For intrastate commerce, Section 350.305 lists the departures a state may make¹¹:

• exempting intrastate vehicles under 26,001 pounds, unless they carry placarded hazardous materials or are designed or used to carry 16 or more people;
• allowing 12 hours of driving with no driving after 16 hours on duty, weekly limits of 70 hours in 7 days or 80 in 8, and a 150 air-mile radius (or the federal short-haul radius, if greater);
• a minimum driver age of 18;
• keeping drivers qualified under earlier state medical standards, and medical variance programs;
• other variances, on application to FMCSA.

A state may not exempt carriers by type of operation, such as for-hire or private, apart from unchanged industry exemptions that predate April 1988, or by distance from the work reporting location beyond the distance exemptions in the FMCSRs themselves¹¹. Intrastate hazardous materials carriers are a partial exception: Section 390.3T(g) applies parts of the federal rules to them directly¹.

The result is a federal floor with a defined set of permitted departures. Which ones a state adopted is a question for its own statutes and administrative code.

Where the text lives

The current text is on the eCFR, the Electronic Code of Federal Regulations, in Title 49, Subtitle B, Chapter III, Subchapter B⁵. The eCFR is updated daily and describes itself as an editorial compilation of CFR material and Federal Register amendments, not yet an official legal edition¹². It keeps dated earlier versions of each section, which matters when the question is what the rule said on the day of a crash.

FMCSA’s interpretations sit elsewhere, in the agency’s Regulatory Guidance portal. The portal states that guidance documents lack the force and effect of law unless a statute authorizes them or a contract incorporates them¹³. Guidance shows how the agency reads a rule. It is not the rule.

The out-of-service criteria are a separate document

Roadside inspections bring in a third text. The North American Standard Out-of-Service Criteria come from the Commercial Vehicle Safety Alliance, a nonprofit association of commercial vehicle safety officials and industry representatives. CVSA calls them the pass-fail criteria for inspections: the violations serious enough to take a driver, vehicle or load off the road until fixed. They are updated every year, effective April 1¹⁴.

The criteria are not part of the FMCSRs. The authority to stop a truck comes from the regulations: Section 396.9 lets FMCSA personnel put a vehicle out of service when its condition or loading would likely cause an accident or a breakdown¹⁵, and Section 395.13 covers drivers over their hours or without current duty-status records¹⁶. Part 385 incorporates the criteria by reference for carriers that hold hazardous materials safety permits¹⁷.

The regulation says what a carrier and driver must do. The criteria say when a shortfall is serious enough to stop the truck at the roadside.