49 U.S.C. § 31142

(a) Inspection of Safety Equipment .— On the instruction of an authorized enforcement official of a State or of the United States Government, a commercial motor vehicle is required to pass an inspection of all safety equipment required under the regulations issued under section 31136. (b) Inspection of Vehicles and Record Retention .— The Secretary of Transportation shall prescribe regulations on Government standards for inspection of commercial motor vehicles and retention by employers of records of an inspection. The standards shall provide for annual or more frequent inspections of a commercial motor vehicle unless the Secretary finds that another inspection system is as effective as an annual or more frequent inspection system. Regulations prescribed under this subsection are deemed to be regulations prescribed under section 31136 of this title . (c) Preemption .— (1) Except as provided in paragraph (2) of this subsection, this subchapter and section 31102 of this title do not— (A) prevent a State or voluntary group of States from imposing more stringent standards for use in their own periodic roadside inspection programs of commercial motor vehicles; (B) prevent a State from enforcing a program for inspection of commercial motor vehicles that the Secretary decides is as effective as the Government standards prescribed under subsection (b) of this section; (C) prevent a State from participating in the activities of a voluntary group of States enforcing a program for inspection of commercial motor vehicles; or (D) require a State that is enforcing a program described in clause (B) or (C) of this paragraph to enforce a Government standard prescribed under subsection (b) of this section or to adopt a provision on inspection of commercial motor vehicles in addition to that program to comply with the Government standards. (2) The Government standards prescribed under subsection (b) of this section shall preempt a program of a State described in paragraph (1)(C) of this subsection as the program applies to the inspection of commercial motor vehicles in that State. The State may not enforce the program if the Secretary— (A) decides, after notice and an opportunity for a hearing, that the State is not enforcing the program in a way that achieves the objectives of this section; and (B) after making a decision under clause (A) of this paragraph, provides the State with a 6-month period to improve the enforcement of the program to achieve the objectives of this section. (d) Inspection To Be Accepted as Adequate in All States .— A periodic inspection of a commercial motor vehicle under the Government standards prescribed under subsection (b) of this section or a program described in subsection (c)(1)(B) or (C) of this section that is being enforced shall be recognized as adequate in every State for the period of the inspection. This subsection does not prohibit a State from making random inspections of commercial motor vehicles. (e) Effect of Government Standards .— The Government standards prescribed under subsection (b) of this section may not be enforced as the standards apply to the inspection of commercial motor vehicles in a State enforcing a program described in subsection (c)(1)(B) or (C) of this section if the Secretary decides that it is in the public interest and consistent with public safety for the Government standards not to be enforced as they apply to that inspection. (f) Application of State Regulations to Government-Leased Vehicles and Operators .— A State receiving financial assistance under section 31102 of this title in a fiscal year may enforce in that fiscal year a regulation on commercial motor vehicle safety adopted by the State as the regulation applies to commercial motor vehicles and operators leased to the Government.