In this subchapter—

((1)) “commercial motor vehicle” means (except in section 31106) a self-propelled or towed vehicle used on the highways in commerce principally to transport passengers or cargo, if the vehicle—

((A)) has a gross vehicle weight rating or gross vehicle weight of at least 10,001 pounds, whichever is greater;

((B)) is designed to transport more than 10 passengers including the driver; or

((C)) is used in transporting material found by the Secretary of Transportation to be hazardous under and transported in a quantity requiring placarding under regulations prescribed by the Secretary under section 5103.

((2)) “employee” means a driver of a commercial motor vehicle (including an independent contractor when personally operating a commercial motor vehicle), a mechanic, a freight handler, or an individual not an employer, who—

((A)) directly affects commercial motor vehicle safety in the course of employment by a commercial motor carrier; and

((B)) is not an employee of the United States Government, a State, or a political subdivision of a State acting in the course of employment.

((3)) “employer”—

((A)) means a person engaged in a business affecting commerce that owns or leases a commercial motor vehicle in connection with that business, or assigns an employee to operate the vehicle in commerce; but

((B)) does not include the Government, a State, or a political subdivision of a State.

((4)) “State” means a State of the United States, the District of Columbia, Puerto Rico, the Virgin Islands, American Samoa, Guam, and the Northern Mariana Islands.