Abbreviation: FMCSR
Federal Motor Carrier Safety Regulations
The body of federal regulations governing commercial motor vehicle safety, primarily found in Title 49 of the Code of Federal Regulations (49 CFR Parts 380–399).
Key parts for CDL compliance: Part 380 (ELDT), Part 382 (drug/alcohol), Part 383 (CDL standards), Part 391 (driver qualifications), Part 395 (hours of service).
Key 49 CFR parts for CDL compliance
Part 380: Entry-Level Driver Training requirements. Part 382: Drug and alcohol testing for CDL drivers in interstate commerce. Part 383: CDL standards — classes, endorsements, restrictions, testing, and disqualification rules. Part 391: Driver qualifications — DQ file requirements, medical certification, and hiring standards. Part 395: Hours of service and ELD requirements. Part 396: Vehicle maintenance, inspection, and DVIR. These parts cross-reference each other frequently — a violation of one often implicates another.
How to access the current CFR text
The Federal Motor Carrier Safety Regulations are published in Title 49 of the Code of Federal Regulations. Current, searchable versions are available on the Electronic Code of Federal Regulations at ecfr.gov — use this instead of unofficial sites to ensure you're reading the current rule text. The eCFR updates as new rules take effect and shows amendment history. For formal legal citations, use the official GPO version at govinfo.gov.
Last updated: June 4, 2026
When this definition matters
This term usually matters when a driver, owner-operator, or small carrier is deciding whether a federal rule applies, preparing a compliance file, or checking a state CDL step. Use this definition as a starting point, then confirm the controlling requirement in the official source listed below before making a licensing, hiring, dispatch, or recordkeeping decision.
The related terms above are included because they often appear in the same compliance workflow. Reviewing them together can prevent common mix-ups, such as treating a state licensing step as a federal carrier obligation or confusing a driver record with a separate employer record.