Drunk driving offenders in California will be required to install an ignition interlock on their vehicles that connects to a breathalyzer under a new law signed by Gov. Jerry Brown on Wednesday.

The law, which takes effect Jan. 1, 2019, is designed to prevent DUI offenders from being able to start their cars if they're drunk.

State Sen. Jerry Hill (D-San Mateo), who authored the bill, says most people with suspended licenses drive anyway, and the interlock is a proven life-saver in the four California counties, including Alameda County, where it has been tested.

"The number of non-starts because of those devices: over 1 million times in five years," Hill said. "In the 25 states where it has been in place for a number of years, the death rate from DUIs was reduced by 40 percent."

The law will require convicted drunk drivers to pass a breathalyzer test connected to their vehicles, and if they fail, the vehicle won't start. A Bay Area woman behind the bill saw her son killed by a drunk driver.

Fifteen years ago, while Matt Klotzbach was on leave from the Naval Academy, he was killed in Los Gatos by a drunk driver with a suspended license. Klotzbach's parents, Tom and Mary Klotzbach, were in the car with him.

"My motivation was that nobody would endure the pain that my family has endured with the loss of Matt," Mary Klotzbach said.

It was a enough motivation for Mary to battle for the statewide mandatory ignition interlock program. She even went as far as installing one of the devices in her own vehicle eight years ago, even though she doesnt drink alcohol.

"I put it on my car because the legislators told me it was draconian to do this," Mary said. "I said this is not draconian; it is using technology to save lives."

Hill said California has 35,000 of the devices, and there are more than 310,000 people with three or more DUIs driving on the highways.

Mothers Against Drunk Driving is sponsoring an event at Lake Merced in San Francisco at 9 a.m. Sunday. It's dedicated to the memory of Matt Klotzbach.