A bill has been introduced in California that would mandate a kill switch for cellphones that have been stolen, prompting concerns that such a system could be abused by authorities in order to stifle dissent.

SB 962 would require that all cellphones sold in the state include software or hardware, “that can render inoperable the essential features of the device, as defined, when the device is not in the possession of the rightful owner.”

Although the owner would have the option to disable the function under the language of the bill, sales of any cellphone that didn’t include the technology would be prohibited.