It's obvious that many of those companies compete not only with Apple, but also with each other. So why come together in support of a business rival?
Box chief executive Aaron Levie, whose cloud-storage company signed onto the brief with Google and others, said there is a clear reason that Silicon Valley is so engaged here: they believe the precedent set in this case affects all of their businesses. Tech firms are eager to have this conversation, he said, because many believe the FBI's request threatens the foundations of all software and product security.
"We need to build technology that is secure and has no known weaknesses," Levie said. "As we get further into the digital age, so much more is being fundamentally driven by these technologies. The future is all going to be about the trust in the security of those technologies."
Levie co-founded Box in 2005 with Box's chief financial officer Dylan Smith -- his friend since middle school -- when a college-aged Levie became frustrated with how difficult it was to share and collaborate on files with other students. The company went public in 2015, after gaining a reputation for having strong security and privacy measures that has made it popular among businesses, including 40 percent of the Fortune 500, and even landed it a contract with the Justice Department.
Box's clients trust their data is secure, Levie said. But if companies such as Apple or Box can be ordered to write code designed to circumvent their security, firms can no longer promise customers their information is completely safe, he said. "Trust is paramount in the business we're in," Levie said. "That trust is broken sometimes, but we have the expectation that companies and tech providers will do everything they can to ensure that their information is secure as humanly possible."
Levie respects the FBI for pursuing an expedient solution to deal with this case, but said this debate must extend beyond one phone and requires extensive discussion.
"If you're a citizen of this country, you are sympathetic to the challenge that FBI is dealing with," he said. "It is absolutely doing its job. The challenge to work through is that there is a higher-level problem at stake here around the health, robustness and security of modern technology."
Levie also called for a broader discussion about how current laws are interpreted to fit new technology. "The Internet's challenges can't always be solved by laws set in stone 50, 100 or 150 years ago," he said. "We're taking precedents set in an analog or industrial world and trying to apply them to digital technology. Those precedents are starting to break down."
A full list of companies that have filed in support of Apple is listed on the company's website. Several groups have also filed briefs in support of the FBI, as my colleague Mark Berman reported. These include relatives of San Bernardino shooting victims, California law enforcement groups including the state's Sheriff's Association, and a joint brief from the National Sheriff's Association, Federal Law Enforcement Officers Association and the Association of Prosecuting Attorneys.
An earlier version of this post misstated the name of Box's CFO. This version has been corrected.