US lawmakers are set to introduce a bipartisan bill that would prohibit states from requiring tech companies to build encryption weaknesses into their products.
The ENCRYPT Act, sponsored by Democrat Ted Lieu and Republican Blake Farenthold, will prevent any state or local government from mandating that a “manufacturer, developer, seller, or provider” design or alter the security of a product so it can be decrypted by local law enforcement.
The legislation is in response to proposals in recent months in New York and California that would require companies to be able to decrypt their smartphones manufactured after 2017.
"It is completely technologically unworkable for individual states to mandate different encryption standards in consumer products," Lieu said.
"Apple can't make a different smartphone for California and New York and the rest of the country."
It is unclear how much momentum the bill will have in the House of Representatives, though the chamber has staked out positions sympathetic to digital privacy in recent years.
The bill is the latest foray into an ongoing debate over encryption between Silicon Valley and Washington.
The issue has gained renewed scrutiny after Apple and Google began offering strong encryption by default on their products in 2014, following revelations of mass surveillance by the NSA.
FBI Director James Comey recently told a Senate panel that federal investigators have still been unable to access the contents of a mobile phone belonging to one of the killers in the December 2 shootings in San Bernardino, California, because of encryption.
But technology companies, privacy advocates and cryptographers say any mandated vulnerability would expose data to hackers and jeopardise the overall integrity of the internet.
A study from the Berkman Centre for Internet and Society at Harvard University released last month, citing some current and former intelligence officials, concluded that fears about encryption are overstated in part because new technologies have given investigators unprecedented means to track suspects.