49 U.S.C. § 30103 — Relationship to other laws

(a) Uniformity of regulations. The Secretary of Transportation cannot set a safety regulation for a motor vehicle covered by subchapter I of chapter 135 (interstate bus and truck operations) that is different from a motor vehicle safety standard already set under this chapter. But the Secretary can still set a stricter performance rule — one that applies after the vehicle is built — for vehicles run by carriers under subchapter I of chapter 135, even if it's tougher than the standard that applied when the vehicle was made. (b) Preemption. (1) Once a motor vehicle safety standard exists under this chapter, a State or a local government can only keep or create its own standard covering that same performance issue if that state or local standard is identical to the federal one. However, the federal government, a State, or a local government can set a tougher performance standard for vehicles or equipment it buys for its own use. (2) A State may enforce a standard that matches the federal one exactly. (c) Antitrust laws. This chapter does not change the antitrust laws. It does not excuse conduct that is already illegal under antitrust law, and it does not ban conduct that is already legal under antitrust law. (d) Warranty obligations and additional legal rights and remedies. Certain sections of this chapter (sections 30117(b), 30118 through 30121, 30166(f), and 30167(a) and (b)) do not create or change any warranty obligation under federal or state law. The remedies in those sections, and in sections 30161 and 30162, are extra — they add to, and don't replace, whatever other rights and remedies already exist under other laws. (e) Common law liability. Following a motor vehicle safety standard set under this chapter does not protect a person from being sued under ordinary common-law liability rules.