Gov. Tom Vilsack has signed a bill banning devices in Iowa that can change some traffic signals from red to green. The effort won widespread support in the Legislature.

The traffic-light changers are designed to allow police, fire and other emergency officials to clear intersections before they approach.

The new law, previously HF717, is intended to deter anyone other than public safety and transit agencies from selling, owning, possessing and/or using mobile infrared transmitters, or MIRTs. Violators face up to 30 days in jail and/or a $500 fine. Anyone caught using the device could also be required to perform community service.

The devices, which sit on a vehicle’s dash, are not regulated by current federal standards because they rely on a beam of light instead of a radio wave to trigger the light-changing mechanisms that have been attached to some intersections.

When a signal changer on a traffic light detects an approaching emergency vehicle equipped with the device, the light responds accordingly. If the light is red, the signal changer will immediately give vehicles in other directions a yellow light, followed by a red light. The emergency vehicle will get a green light until it passes through the intersection.

The new law takes effect Aug. 15.