§390.9 — State and local laws, effect on Except as otherwise specifically indicated, subchapter B of this chapter is not intended to preclude States or subdivisions thereof from establishing or enforcing State or local laws relating to safety, the compliance with which would not prevent full compliance with these regulations by the person subject thereto.
§390.9 — DOT Regulatory Guidance
Question 1: If an interstate driver gets stopped by a State enforcement officer for an inspection, would the inspecting officer be enforcing the Federal regulations or State regulations? Guidance: A State enforcement officer can only enforce State laws. However, under the Motor Carrier Safety Assistance Program, quite often State laws are the same as or similar to the FMCSRs.