An enlightened measure signed this month by California’s Republican governor, Arnold Schwarzenegger, will require those convicted of drunken driving — including first-time offenders — to install special devices that prevent cars from operating if the driver is drunk. The large pilot program, which covers the 14 million people living in Los Angeles, Sacramento and two other counties, adds important momentum to the national campaign by Mothers Against Drunk Driving to expand the use of the life-saving technology.

Mandating the ignition-interlock devices for all drunken-driving offenders is smart safety policy. Once installed, the vehicle will not start until the driver first blows into the device and registers an alcohol level below the legal limit. Offenders who commute to work by car can keep their jobs, but they cannot drink and drive.

This technical fix is more effective than just a license suspension. Up to three-quarters of drunken drivers whose licenses are suspended continue to drive. Typically, a first-time, convicted offender has driven under the influence dozens of times before being arrested.

There are 11 states that require both first offenders and repeaters to use ignition-interlock devices for an assigned period. Most programs were enacted in the past two years, and the data are still building. But for California, where recidivists make up more than a quarter of annual drunken-driving arrests, the dramatic results logged in New Mexico are encouraging. Between 2004 and 2008, New Mexico experienced a 65 percent drop in drunken-driving recidivism. Drunken-driving fatalities in the state dropped 35 percent.

California’s large-scale embrace of interlocks should help embolden lawmakers in states like New York, where similar proposals face predictable, shortsighted opposition from the alcohol industry. Congress should also take action by conditioning federal highway money on requiring ignition interlocks for all convicted drunken-driving offenders.