Washington Revised Code Title 46. Motor Vehicles § 46.37.395. Compression brakes (Jake brakes)

(1) This section applies to all motor vehicles with a gross vehicle weight rating of 4,536 kilograms or more (10,001 pounds or more), registered and domiciled in Washington state, operated on public roads and equipped with engine compression brake devices. An engine compression brake device is any device that uses the engine and transmission to impede the forward motion of the motor vehicle by compression of the engine.

(2) The driver of a motor vehicle equipped with a device that uses the compression of the motor vehicle engine shall not use the device unless: The motor vehicle is equipped with an operational muffler and exhaust system to prevent excess noise. A muffler is part of an engine exhaust system which acts as a noise dissipative device. A turbocharger is not permitted to be used as a muffler or a noise dissipative device.

(3) The monetary penalty for violating subsection (2) of this section is: (a) Two hundred fifty dollars for the first violation; (b) five hundred dollars for the second violation; and (c) seven hundred fifty dollars for each violation thereafter.

(4) All medium and heavy trucks must comply with federal code 205--transportation equipment noise emission controls, subpart B.

(5) Nothing in this section prohibits a local jurisdiction from implementing an ordinance that is more restrictive than the state law and Washington state patrol rules regarding the use of compression brakes.