Today saw the deadline for amicus briefs in the heated iPhone security trial, and several companies and interested parties took the opportunity to make their case before the court.

The most significant brief came from Google, Microsoft, Facebook, Amazon, Evernote, and nine other major firms, which emphasized the severe harm that would come from court-initiated mandate as opposed to a more considered legislative action. "[The signed companies] pride themselves on transparency with the public, particularly with respect to sensitive issues such as disclosing users’ data," the decision reads. "A boundless All Writs Act could cripple these efforts."

"A boundless All Writs Act could cripple these efforts."

Twitter, Reddit, Github, Ebay, and CloudFlare also submitted a brief with 12 other startup companies, emphasizing the values of privacy and transparency in online services. "If the government is able to compel companies to break their own security measures," the companies write, "the users of those companies will necessarily lose confidence that their data is being handled in a secure, open manner."

Earlier today, a group of security experts also filed a brief emphasizing the risks of developing the software the FBI has requested. Further briefs came from WordPress and Automattic, as well as Intel. A joint brief was filed by a number of industry advocacy groups, including the Software Alliance, the Consumer Technology Association, the Information Technology Industry Council, and TechNet. A number of non-profit advocacy groups have also filed in support of Apple's case, including the ACLU, EFF, Access Now, the Center for Democracy and Technology, and Privacy International. Apple has collected a number of the briefs here.

"Only Congress can address these issues."

Not all of the briefs were in Apple's favor. The court also received a brief from the Federal Law Enforcement Officers Association, Association of Prosecuting Attorneys, and National Sheriffs' Association, which stressed the importance of information-gathering methods. Relatives of victims of the attack also submitted a brief in favor of the government's position, as had been previously announced to the press. Notably, the action only signed on relatives of six victims of the attack, which left fourteen dead and 22 wounded. The husband of another victim has submitted a letter to the court in Apple's favor.

The most measured support came from AT&T, which recommended vacating the order against Apple in favor of Congressional action. "Only Congress can address these issues in a sufficiently comprehensive, uniform, and fair manner," a company statement explains. "All of us—the government, the courts, consumers and companies—need clear and uniform rules that can be produced only through a broadly-informed, transparent and accountable legislative process."

Notably, the statement stopped short of championing many of the privacy rights put forward by Apple's supporters. "The issue before this court is not whether the government should secure evidence critical to the [San Bernardino] investigation," AT&T said. "Of course it should."

None of the filings have legal force, but they're offered as a way to inform the court's decision and their arguments may be influential in the weeks to come. The next major proceeding will be on March 22nd, when the court hears arguments for both Apple's relief motions and the government's motion to compel.

7:02PM ET: Updated to include briefs from victims' families and more detail on the Google et al brief.

7:14PM ET: Updated with the text of the Google et al brief.