Gov. Kathleen Blanco signed a bill into law June 23 outlawing devices in Louisiana that can change some traffic signals from red to green.

The traffic control pre-emption devices are designed to allow police, fire and other emergency officials to clear intersections before they approach. But some drivers have managed to purchase them on the Internet for about $325, The Times-Picayune reported.

The new law, previously HB188, bans the purchase, selling or use of a so-called mobile infrared transmitter, or MIRT, by anyone other than public safety and transit agencies.

It stipulates that violators of the ban be jailed for up to a year, fined a maximum of $5,000, or both.

The devices, which sit on a vehicle’s dash, are not regulated by 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.

A recent U.S. Department of Transportation survey showed there are 26,500 intersections in 78 cities across the country equipped with the devices.

State Police spokesman Lt. William Davis recently told the newspaper he is unaware of any serious problems with the devices in Louisiana but said if the devices become popular and drivers start using them “it would cause mayhem” with traffic, increasing accidents, injuries and fatalities.

The new law will take effect Aug. 15.