California officials have proposed that the state require all smartphones and tablets be sold with a "kill switch" function in case the devices are stolen.

State Sen. Mark Leno (D-San Francisco) and other lawmakers plan to propose legislation requiring all new smartphones and tablets sold in California to have a kill switch or similar protection starting Jan. 1, 2015, the Los Angeles Times reported.

"This legislation is critical to reducing robberies," Los Angeles Mayor Eric Garcetti wrote to legislators this week, according to the L.A. Times.

The city had a 12 percent increase in stolen mobile devices in 2012 (the most recent available numbers), and such thefts make up around a third of all robberies in the country, according to data from the Federal Communications Commission.

"The wireless industry must take action to end the victimization of its customers," San Francisco Dist. Atty. George Gascon said in a statement, as quoted by the L.A. Times.

More than half of all robberies in San Francisco involve stolen smartphones or tablets, he said.

Tech industry officials seem apprehensive of government involvement, and some companies have already implemented security measures on their own; for example, Apple included a lockout feature on the latest iOS version.

"In general, we agree that it's smart to try to engage technology to improve public safety," John Doherty, a vice president of the industry group TechNet, told the L.A. Times.

"But we are going to be very cautious about attempts to legislatively mandate future technology in products," Doherty noted. "That impacts consumer price. That impacts innovation. And there are always unintended consequences."

Paul Boken of Illinois, who supports the California proposal, became an activist for theft-deterrent technology after Megan, his daughter, was killed in 2012 by an armed man trying to steal her phone.

"The theft of a smartphone ended my daughter's life and forever changed mine," Boken said.

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