New Mexico Gov. Gary Johnson has signed into law a bill requiring installation of ignition locks in the vehicles of repeat drunken drivers and first-time offenders. The ignition lock prevents a vehicle from starting if the driver, who must blow into it, has a blood alcohol level of more than 0.02 percent. Under current law, judges can order the devices installed, but it’s not mandatory. It’s estimated that about 500 devices have been used statewide. The device will cost the driver $60 to install or $2 a month to rent.