On Monday, California Governor Jerry Brown signed into law a piece of legislation mandating that all smartphones come with kill-switch software automatically installed so that a user can remotely wipe his or her device if it gets stolen. The bill will affect all smartphones manufactured after July 1, 2015 to be sold in California.

After that date, new smartphones will prompt users to set up a wiping feature, but users will be able to opt out as well. As part of the legislation, anyone caught selling stolen phones will be fined a civil penalty of between $500 and $2,500.

As Ars noted two weeks ago when the bill passed the state senate, the legislation's supporters included the cities of Los Angeles, Oakland, San Diego, and San Francisco, as well as several consumer unions, police groups, and the Utility Reform Network. Its opponents included a couple of municipal Chambers of Commerce, the wireless industry lobby CTIA, and the Electronic Frontier Foundation.

The California government hopes to cut down on phone theft, and laws like this tend to spread to other states if manufacturers decide that the cost of making the change for one state is high enough to extend the change to all states. “Starting next year, all smartphones sold in California, and most likely every other state in the union, will come equipped with theft deterrent technology when they purchase new phones,” Senator Mark Leno (D-San Francisco) said in a press release today.

The same press release noted that Apple, AT&T, Blackberry, Google, Microsoft, Samsung, and Verizon all removed their opposition to the bill. Smartphone companies originally opposed the bill saying that the kill switch could be used by malicious hackers, but the same companies were also in a position to gain considerably from passively allowing theft due to deals with device insurance companies.

The EFF has also opposed the bill (and remains opposed to the law), saying that companies like Find my iPhone and Lookout already offer the option to wipe a phone to consumers. The digital civil liberties group also says that it's unclear from the legislation whether government actors could authorize turning the kill-switch on a phone.