Mr. David Hutton
21-23 East Street
Hants PO13 0BZ
Dear Mr. Hutton:
This responds to your letter asking about the relationship between U.S. Federal laws and State laws. You indicated that you have been involved for many years with the National Highway Traffic Safety Administrations (NHTSAs) regulations regarding the equipment installed in motor vehicles, mainly the safety and associated standards under 49 CFR Part 571. You stated that you understand that "no US state can enforce a regulation which is different to the Federal regulation, however, they can make rules where no federal rule exists."You asked whether this position is "laid down in any laws."
NHTSA is an agency within the U.S. Department of Transportation. Congress has authorized the Secretary of Transportation to issue Federal motor vehicle safety standards applicable to new motor vehicles and items of motor vehicle equipment under the National Traffic and Motor Vehicle Safety Act, which is now codified as 49 U.S.C. Chapter 301. The Secretary has delegated that responsibility to NHTSA.
Chapter 301 includes a section addressing the relationship to other laws ( 30103, copy enclosed). Paragraph (b) of that section addresses the issue you asked about:
(1) When a motor vehicle safety standard is in effect under this chapter, a State or a political subdivision of a State may prescribe or continue in effect a standard applicable to the same aspect of performance of a motor vehicle or motor vehicle equipment only if the standard is identical to the standard prescribed under this chapter. However, the United States Government, a State, or a political subdivision of a State may prescribe a standard for a motor vehicle or motor vehicle equipment obtained for its own use that imposes a higher performance requirement than that required by the otherwise applicable standard under this chapter.
(2) A State may enforce a standard that is identical to a standard prescribed underthis chapter.
I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama of my staff at this address or by telephone at (202) 366-2992.