What is driving Apple's fight against the FBI? Critics question motives.

The saga of Apple’s fight against a Federal Bureau of Investigation request for assistance in breaking into an iPhone continues to gather pace.

Other major tech companies are lining up to offer Apple support in its efforts to protect privacy, and myriad other people and organizations are wading into the fray with their own opinions, not all of which are quite so sympathetic with the stance of the iPhone producer.

Both Apple and the federal government appear to be digging into the history books as they search for legal precedents to defend their corners.

“The United States government has demanded that Apple take an unprecedented step which threatens the security of our customers,” wrote Apple CEO Tim Cook in a statement Tuesday. “We oppose this order, which has implications far beyond the legal case at hand.”

Google’s chief executive officer Sundar Pichai has voiced support, talking of “a troubling precedent”, Twitter’s CEO Jack Dorsey tweeted, “We stand with @tim_cook and Apple (and thank him for his leadership!),” and Facebook has also spoken in solidarity.

The FBI has filed a request that would require Apple to essentially construct a back door into the iPhone used by one of the shooters involved in the Dec. 2 terrorist rampage in San Bernadino, Calif.

While the government insists the mechanism would only be used this one time, the general concern is that, once created, it would unleash a Pandora’s Box.

Not only could the technology never be uncreated, but a legal precedent would also be set, giving surveillance the upper hand over privacy, privacy advocates say.

“If the order stands, Apple and other technology companies could be ordered to build backdoors – essentially defects – into other devices, rendering them insecure and vulnerable to attack by law enforcement and by others as well,” wrote Director of the Freedom, Security and Technology Project at the Center for Democracy & Technology, Greg Nojeim. “We will fight against this result.”

Yet support for Apple is not universal.

Some question its motives and assert that as Mr. Cook has set himself up as a grand defender of privacy, he had no choice but to fight this battle or lose all credibility.

“As a general matter of strategic communications, following the words 'We have no sympathy for terrorists' with a 'But' generally means you’ve gone badly off message – even if you wedge a few sentences in between,” writes Susan Hennessey and Benjamin Wittes of The Brookings Institution.

“Apple is being mischievous here, and the company’s self-presentation as crusading on behalf of the privacy of its customers is largely self-congratulatory nonsense.”

In seeking to defend its stance, Apple will likely cite the United States’ protections of free speech, as Reuters notes, having already retained the services of two prominent free-speech lawyers.

For its part, the US Department of Justice has founded its request for Apple’s assistance on various legal authorities, including the All Writs Act of 1789 and subsequent rulings based thereon.

This case represents the culmination of an argument that has been simmering for some time, a quest to find the right balance between privacy and security.

As Mr. Pichai of Google tweeted, “Looking forward to a thoughtful and open discussion on this important issue.”

This report contains material from Reuters and the Associated Press.