New smartphones sold in the United States would have to contain a mechanism to brick the devices remotely, wiping data and rendering them inoperable, under legislation proposed Friday by four Democratic U.S. senators.

The four -- Amy Klobuchar (D-MN), Barbara Mikulski (D-MD), Richard Blumenthal (D-CT), and Mazie Hirono (D-HI) introduced the Smartphone Theft Prevention Act to require a “kill switch” on smartphones to help protect consumers and deter thieves.

Some smartphones like recent iPhone and iPad models, already have this technology.

“Cell phone theft has become a big business for thieves looking to cash in on these devices and any valuable information they contain, costing consumers more than $30 billion every year and endangering countless theft victims,” Klobuchar said in a release on her senate website. “This legislation will help eliminate the incentives for criminals to target smartphones by empowering victims to take steps to keep their information private, protect their identity and finances, and render the phone inoperable to the thieves.”

The bill resembles a recent California proposal requiring mobile device manufacturers to be able to brick a phone remotely. The California bill, however, applies much more broadly, notes tech site Re/Code, because it may apply to any hand held communications device including book readers and touchscreen tablets that are Wi-Fi only.

A built-in kill switch has its drawbacks. If a thief can switch out a SIM card before a subscriber calls in the theft, the kill switch won't work. A hacker could abused a kill-switch function to brick the phone of a target ... like a police officer. And while the proposed federal legislation would make it a crime to tamper with the electronic identification on a phone to evade the kill-switch, that would also make it more difficult for security-conscious subscribers to mask their phones from government surveillance.

The Federal Communications Commission recently began an anti-theft initiative noting that more than 40 percent of robberies in New York City involve smartphones and other cell phones, and that about one in three robberies involve the theft of a smartphone.

Carriers completed construction of a stolen smartphone database in November. The database itself has limited usefulness, however, since a stolen smartphone sold overseas makes a domestic database useless.

But observers note that there's been some resistance by these carriers to implementing a mandatory kill-switch policy because carriers profit from stolen cell phone insurance and may not be making robust use of the stolen smartphone databases they've just finished building.