(a) The purpose of this part is to establish under the influence of alcohol or a dangerous drug standards under 46 U.S.C. 2302 and to prescribe restrictions and responsibilities for personnel on vessels inspected, or subject to inspection, under Chapter 33 of Title 46 United States Code. This part does not pre-empt enforcement by a State of its applicable laws and regulations concerning operating a recreational vessel while under the influence of alcohol or a dangerous drug.

(b) Nothing in this part shall be construed as limiting the authority of a vessel's marine employer to limit or prohibit the use or possession of alcohol on board a vessel.