Title 49 — TransportationRelease 119-73
§31147 Limitations on authority
Title 49 › Subtitle SUBTITLE VI— - MOTOR VEHICLE AND DRIVER PROGRAMS › Part PART B— - COMMERCIAL › Chapter CHAPTER 311— - COMMERCIAL MOTOR VEHICLE SAFETY › Subchapter SUBCHAPTER III— - SAFETY REGULATION › § 31147
Summary
The Secretary of Transportation cannot make traffic safety rules or override state traffic laws, except for topics that were already covered under 49 CFR parts 390–399 on October 30, 1984. The Secretary also cannot make rules about how commercial motor vehicles are built for any reason, including fuel economy, safety, or emissions.
Full Legal Text
Title 49, §31147
Transportation — Source: USLM XML via OLRC
(a)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)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
Apr 6, 2026
Release point: 119-73