Title 49, TransportationRelease 119-110
§31147 Limitations on Authority
Title 49 › SUBTITLE VI — MOTOR VEHICLE AND DRIVER PROGRAMS › PART B — COMMERCIAL › CHAPTER 311 — COMMERCIAL MOTOR VEHICLE SAFETY › SUBCHAPTER III — SAFETY REGULATION › § 31147
Summary
The Secretary of Transportation cannot make traffic safety rules or override state traffic laws, except for matters that were already handled in parts 390–399 of title 49, Code of Federal Regulations as of October 30, 1984. The Secretary also cannot regulate how commercial motor vehicles are made for any purpose, including fuel economy, safety, or emission control.
Full Legal Text
Title 49, §31147
Transportation, Source: USLM XML via OLRC
(a)Traffic Regulations.—
This subchapter does not authorize the Secretary of Transportation to prescribe traffic safety regulations or preempt State traffic regulations. However, the Secretary may prescribe traffic regulations to the extent their subject matter was regulated under parts 390–399 of title 49, Code of Federal Regulations, on October 30, 1984.
(b)Regulating the Manufacturing of Vehicles.—
This subchapter does not authorize the Secretary to regulate the manufacture of commercial motor vehicles for any purpose, including fuel economy, safety, or emission control.
Legislative History
Notes & Related Subsidiaries
Historical and Revision Notes
Revised SectionSource (U.S. Code)Source (Statutes at Large) 31147(a)49 App.:2519(a).Oct. 30, 1984, Pub. L. 98–554, § 229, 98 Stat. 2853. 31147(b)49 App.:2519(b). In subsection (a), the word “prescribe” is substituted for “establish or maintain” for consistency in the revised title and with other titles of the United States Code.
Reference
Citations & Metadata
Citation
49 U.S.C. § 31147
Title 49, Transportation
Last Updated
Sep 22, 2026
Release point: 119-110