Perhaps surprisingly, the two leading US operators are backing Apple in its refusal to create a backdoor into iOS.

AT&T followed rival Verizon in supporting Apple and opposing the FBI which last month obtained a court order requiring the smartphone giant to create a backdoor into an iPhone used by one of the perpetrators of a December shooting in San Bernardino, California.

In a statement, AT&T senior executive vice president and general counsel, David McAtee, said the court order required Apple to “take some fairly extraordinary steps” to assist the FBI.

McAtee argued against ad hoc rulings by judges and in favour of Congress providing a clear, legal framework for all players in the digital economy. “The solution is for Congress to pass new legislation that provides real clarity for citizens and companies alike,” he said.

Reuters interpreted McAtee’s comments as a reference to the Communications Assistance for Law Enforcement Act (CALEA) of 1994, which covers operators but excludes so-called “information services”, taken to mean internet companies.

A separate filing claimed the court order in favour of the FBI was wrong because CALEA clearly laid out who had to enable communication interception by law enforcers. And Apple was not included in the definition, they argued.

Quartz noted that AT&T’s position was perhaps surprising given its past record of support for government surveillance. Whistleblower Edward Snowden revealed that AT&T was willing to help the US National Security Agency over many years, including offering technical assistance in wiretapping its subscribers and installing surveillance equipment in its hubs.

In addition to AT&T, a large number of tech companies filed so-called amicus briefs in support of Apple. Amicus briefs are filings made by non-litigants with a particular interest in the subject matter of a court case. A 2 March deadline drew support for Apple from a range of tech companies, in addition to AT&T. They included Google, Facebook, Microsoft, Mozilla, Twitter and LinkedIn.