In this subchapter—

(1) “commercial motor vehicle” means a self-propelled or towed vehicle used on the highways in interstate commerce to transport passengers or property, 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 or used to transport more than 8 passengers (including the driver) for compensation;

(C) is designed or used to transport more than 15 passengers, including the driver, and is not used to transport passengers for compensation; or

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

(2) “employee” means an operator of a commercial motor vehicle (including an independent contractor when 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; 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 the employment by the Government, a State, or a political subdivision of a State.

(3) “employer”—

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

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

(4) “interstate commerce” means trade, traffic, or transportation in the United States between a place in a State and—

(A) a place outside that State (including a place outside the United States); or

(B) another place in the same State through another State or through a place outside the United States.

(5) “intrastate commerce” means trade, traffic, or transportation in a State that is not interstate commerce.

(6) “medical examiner” means an individual licensed, certified, or registered in accordance with regulations issued by the Federal Motor Carrier Safety Administration as a medical examiner.

(7) “regulation” includes a standard or order.

(8) “State” means a State of the United States, the District of Columbia, and, in sections 31136 and 31140-31142 ¹ of this title, a political subdivision of a State.

(9) “State law” includes a law enacted by a political subdivision of a State.

(10) “State regulation” includes a regulation prescribed by a political subdivision of a State.

(11) “United States” means the States of the United States and the District of Columbia.