States' responsibilities regarding compliance.

(a) States are responsible for ensuring compliance with 23 U.S.C. 164 and this part. (b) A State that has been determined to be in compliance with the requirements of 23 U.S.C. 164 and this part must promptly notify the appropriate NHTSA Regional Administrator in writing of any change or change in enforcement of the State's repeat intoxicated driver law, identifying the specific change(s).