Privacy advocates and some users criticized the move, which came to light on Thursday as Apple Inc. was waging an legal battle over unlocking an iPhone.
The rare display of unity and support from Apple's sometime-rivals showed the breadth of Silicon Valley's opposition to the government's anti-encryption effort, a position endorsed by the United Nations human rights chief.
In a copy of the brief provided by the company, Apple argued that the government's request is 'unprecedented' and violates the company's First Amendment rights.
