Two US senators have issued a formal draft of a controversial bill that would give courts the power to order companies like Apple to help authorities break into encrypted devices or communications.
The bill comes as the US Justice Department has redoubled its efforts to use the courts to force Apple to unlock encrypted iPhones.
Senators Richard Burr and Dianne Feinstein, the Senate intelligence committee's Republican chair and leading Democrat, said in a statement they intended now to "solicit input from the public and key stakeholders before formally introducing the bill".
"I am hopeful that this draft will start a meaningful and inclusive debate on the role of encryption and its place within the rule of law," Burr said.
"Based on initial feedback, I am confident that the discussion has begun."
The new discussion draft does not require manufacturers or communications companies to process, transmit or store data in any particular format.
Instead, it requires companies, upon receipt of a court order, to turn over to the government "data in an intelligible format" even if encryption has rendered that data inaccessible to anyone other than the owner.
Cases where a court can issue an order include crimes that caused or could cause death or serious injury, that involve drug offences, child victims, in addition to foreign intelligence operations.
Companies must ensure their products are "capable of complying", the bill states. Critics say that amounts to a ban on strong encryption.
The proposal arrives just days after an earlier draft leaked online and drew fire from security researchers and civil liberties advocates who warned it would undermine internet security and expose personal data to hackers.
Those same groups on Wednesday said the new draft is little different from the leaked version.
Electronic Frontiers Foundation staff attorney Andrew Crocker said changes in the new discussion draft were minimal and the bill still threatened internet security because companies would only be able to comply by weakening encryption in all their products.
The proposed legislation, which is expected to continue facing strong opposition from the technology sector and privacy advocates, faces an uphill battle in a gridlocked Congress.
"This flawed bill would leave Americans more vulnerable to stalkers, identity thieves, foreign hackers and criminals," said Democratic Senator Ron Wyden in a statement.
The proposal comes after the US Justice Department recently unlocked an encrypted iPhone used by one of the San Bernardino shooters and dropped its legal case against Apple, ending a high-stakes legal battle.