Michigan Compiled Laws, Chapter 324. Natural Resources and Environmental Protection § 324.6304

Sec. 6304. (1) “Pollutants” means nitrogen oxides, carbon monoxide, hydrocarbons, and other toxic substances emitted from the operation of a motor vehicle.

(2) “Public inspection station” means a facility for motor vehicle inspection operated under contract with the department as provided in this part.

(3) “Tamper with” means to remove or render inoperative, to cause to be removed or rendered inoperative, or to make less operative an emission control device or an element of an emission control device that is required by the clean air act to be installed in or on a motor vehicle.

(4) “Test-only network” means a network of inspection stations that perform official vehicle emissions inspections and in which owners and employees of those stations, or companies owning those stations, are contractually or legally barred from engaging in motor vehicle repair or service, motor vehicle parts sales, and motor vehicle sale and leasing, either directly or indirectly, and are barred from referring vehicle owners to particular providers of motor vehicle repair services.