49 CFR § 655.6 - Preemption of state and local laws.
(1) Compliance with both the state or local requirement and any requirement in this part is not possible; or
(2) Compliance with the state or local requirement is an obstacle to the accomplishment and execution of any requirement in this part.
(b) This part shall not be construed to preempt provisions of state criminal laws that impose sanctions for reckless conduct attributed to prohibited drug use or alcohol misuse leading to actual loss of life, injury, or damage to property, whether the provisions apply specifically to transportation employees or employers or to the general public.
The following state regulations pages link to this page.