The bandwagon of supporters in Apple's fight against the FBI keeps getting bigger.

Amazon, Facebook, Google and Microsoft, along with 11 other companies, filed on Thursday a joint amicus brief, a court filing that throws their support behind Apple as it prepares to face off against the US government in federal court later this month.

"The government is not just asking companies to do what they do in the normal course of business; the government is asking companies to change how they do business," they said in their filing. But while they noted that they don't have any sympathy for terrorists, the companies added that "cell phones are the way we organize and remember the things that are important to us; they are, in a very real way, an extension of our memories. And as a result, to access someone's cell phone is to access their innermost thoughts and their most private affairs."

Their show of support came after Twitter, Airbnb, LinkedIn and 13 other companies filed a separate joint amicus brief, and Intel and AT&T submitted their own filings. Apple also has the support of top industry groups, including the Consumer Technology Association, Information Technology Industry Council, TechNet and the BSA/Software Alliance. The Electronic Frontier Foundation was joined by 46 cryptographers, researchers and technologists in their pro-Apple filing. Privacy International and the Human Rights Watch jointly filed their own brief.

The American Civil Liberties Union on Wednesday was the first to file its support for Apple in a brief on Wednesday.

Apple is compiling a list of all the briefs filed in its behalf on its website. The amicus briefs are due to the court by today.

The tech world has largely sided with Apple CEO Tim Cook, with everyone ranging from mobile executives at a conference in Barcelona, Spain, to cybersecurity experts gathered in San Francisco getting behind the iPhone maker.

That's because despite their differences, they agree with Apple's argument that being forced by the US to create special software to break into its encrypted iPhone sets a dangerous precedent that could leave all of our devices vulnerable. This so-called security "back door" concept can be applied to everything from a phone running on Google's Android software to a PC running on Microsoft's Windows 10 to personal medical devices.

"The target of the government's request in this case is Apple, but the government's theory would just as easily extend to any third-party developer that has as one of its functions collecting and storing personal information about the device's owner," the coalition of trade groups said in a 19-page joint brief. "The authority sought by the government would therefore extend not only to phones, laptop computers and tablets, but also to automobiles that store information regarding location and times of use; insulin pumps that store information about blood sugar levels; and the myriad other devices that collect and store personal information."

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The FBI argues the situation is specific to the single iPhone 5C used by one of the terrorists involved in a December massacre in San Bernardino, California, in which 14 people died and 20 others were wounded.

The US has argued that having such secure zones, which are completely off limits to authorities, create a safe haven for criminals.

At least one amicus brief was filed Thursday in support of the FBI. Several family members of San Bernardino shooting victims urged that the court "not be led astray by Apple's grandstanding."

"Recovery of information from the iPhone in question may not lead to anything new. But, what if there is evidence pointing to a third shooter? What if it leads to an unknown terrorist cell?" wrote Mark Sanfeur, whose son was among those killed in the attack.

"What if others are attacked, and you and I did nothing to prevent it?" Sanfeur wrote in a letter to Apple's CEO included in the brief filed by attorney Stephen Larson of the Los Angeles-based law firm of Larson O'Brien.

The tech industry, based on today's filings, shows just how strongly they disagree.

"It would set a dangerous precedent, creating a world in which the government could simply force companies to create, design, and redesign their systems to allow law enforcement access to data, instead of requiring the government to use the measures, and meet the requirements, of legislatively enacted statutory schemes," the group including Twitter, LinkedIn and Airbnb wrote in its 26-page amicus brief.

"Granting the government such extraordinary authority, without any set rules or legal protections, will not only erode user privacy and security and defeat users' interest in transparency, it will undermine an existing legislative framework balancing competing interests and policy considerations," they added. "Despite consistent advocacy from the FBI for nearly 20 years, Congress has yet to advance, much less pass, legislation that would require companies like Apple to ensure governmental access to data on the devices it sells to the public."

While the tech world is in alignment, the public is not. The Pew Research Center found that 51 percent of those surveyed believe Apple should comply with the court order, while 38 percent said the company shouldn't unlock the iPhone. A later Reuters poll found 46 percent of respondents agreed with Apple's position and 35 percent disagreed.

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A court hearing to determine whether Apple should be forced to comply with the FBI's request is set for March 22 in federal court in Riverside, California. Earlier this week, Apple's top lawyer, Bruce Sewell, spoke on a panel opposite FBI Director James Comey debating personal security versus national security in a five-hour session on Capitol Hill.

Sewell is on the executive council of TechNet, which boasts leaders such as Cisco Chairman John Chambers, Alphabet Executive Chairman Eric Schmidt, Oracle CEO Safra Catz and other power players.

While AT&T has asked the court to dismiss the FBI request, the Dallas telecommunications giant also made a plea for the government to settle the debate. "Congress is the right body to weigh the compelling, but competing, interests in privacy and security," the company said in its filing.

Apple already scored some legal backing after a US District Court judge on Monday dismissed a similar request on a different case involving a drug dealer in Queens, New York. In that situation, the authorities had used the All Writs Act, a 227-year law enacted under President George Washington, to compel Apple to help break into the suspect's phone. That's the same law that the FBI is using in the San Bernardino case.

Following the ruling, an Apple executive said the New York ruling could sway the San Bernardino case. The Department of Justice said it was "disappointed" by the ruling and will continue to challenge the order in the court system.

Facebook, Google, Amazon and others, in their filing, reinforced their view that the FBI's request will affect the entire tech industry -- and the products themselves. "With enough time and resources, [our] engineers could possibly come up with any number of new versions of their companies' products that circumvent or undermine their pre-existing data-security features. But those new versions would not be the same product anymore. Snapchat would not be Snapchat; Box would not be Box; Gmail would not Gmail; WhatsApp would not be WhatsApp; and so on."

You can find all our coverage related to Apple vs. the FBI here.

CNET's Connie Guglielmo, Richard Nieva and Terry Collins contributed to this report.



Update, March 3, 4:31 p.m. PT: Adds additional amicus brief from Google, Facebook, Amazon and other companies.

Victims' families' amicus brief