18 U.S. Code § 39 - Traffic signal preemption transmitters
(1) Sale.— Whoever, in or affecting interstate or foreign commerce, knowingly sells a traffic signal preemption transmitter to a nonqualifying user shall be fined under this title, or imprisoned not more than 1 year, or both.
(b) Definitions.— In this section, the following definitions apply:
(1) Traffic signal preemption transmitter.— The term “traffic signal preemption transmitter” means any mechanism that can change or alter a traffic signal’s phase time or sequence.
(2) Nonqualifying user.— The term “nonqualifying user” means a person who uses a traffic signal preemption transmitter and is not acting on behalf of a public agency or private corporation authorized by law to provide fire protection, law enforcement, emergency medical services, transit services, maintenance, or other services for a Federal, State, or local government entity, but does not include a person using a traffic signal preemption transmitter for classroom or instructional purposes.