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FMCSA Regulations
Starter page for Title 49, FMCSA regulations, and public regulatory resources.
What Are the FMCSRs?
The Federal Motor Carrier Safety Regulations (FMCSRs) are the core body of federal safety rules that govern commercial motor vehicle operations in interstate commerce. They are issued by FMCSA, part of the U.S. Department of Transportation, and codified in 49 CFR Parts 300–399. Related rules that trucking companies also need to know include the drug and alcohol testing procedures in 49 CFR Part 40 and the Hazardous Materials Regulations (HMR) in 49 CFR Parts 100–180, which apply to carriers that transport hazardous materials.
Key Parts at a Glance
| Part | Subject |
|---|---|
| Part 382 | Controlled substances and alcohol use and testing |
| Part 383 | Commercial driver's license (CDL) standards |
| Part 385 | Safety fitness procedures, safety audits, and compliance reviews |
| Part 387 | Minimum levels of financial responsibility (insurance) |
| Part 390 | General applicability and recordkeeping requirements |
| Part 391 | Driver qualification requirements |
| Part 392 | Driving rules of conduct behind the wheel |
| Part 393 | Vehicle parts and accessories necessary for safe operation |
| Part 395 | Hours of service of drivers |
| Part 396 | Inspection, repair, and maintenance of vehicles |
| Part 397 | Transportation of hazardous materials, driving and parking rules |
Who Has to Comply
The FMCSRs generally apply to commercial motor vehicles operated in interstate commerce that meet certain size, weight, or passenger-capacity thresholds, and to the drivers and carriers that operate them. Some states apply similar or identical standards to intrastate operations as well. Because the applicability rules involve several defined terms — "commercial motor vehicle," "interstate commerce," "for-hire" versus "private" carriage — carriers should confirm exactly which parts apply to their specific operation rather than assume based on vehicle size alone.
How the Rules Are Enforced
FMCSA and its state partners enforce the FMCSRs primarily through roadside inspections, the Compliance, Safety, Accountability (CSA) program and its Safety Measurement System (SMS), and on-site compliance reviews. Violations found through any of these channels feed into a carrier's safety record and can lead to warning letters, safety ratings, civil penalties, or out-of-service orders depending on severity.
Frequently Asked
Where do I find the official, current text of a regulation?
Do state rules ever differ from the federal FMCSRs?
How often do the FMCSRs change?
Related Topics
This page is general information, not legal advice. The FMCSRs and HMR are issued and amended by FMCSA and PHMSA and are subject to change — always confirm current, applicable requirements at ecfr.gov or fmcsa.dot.gov before making compliance decisions.
Free Resources
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Regulations (FMCSA regulatory hub)
FMCSA
Central FMCSA page linking to Title 49 CFR Parts 300-399 and the full federal motor carrier safety regulations.