As expected, federal prosecutors filed their formal response on Thursday in the ongoing case involving the seized iPhone 5C that was used by one of the shooters in the San Bernardino terrorist attack in December 2015.

Last month, the government obtained an unprecedented court order under the All Writs Act, an obscure 18th-century statute, which would compel Apple to assist in the government's investigation. If the order stands up to legal challenges, Apple would be forced to create a new customized iOS firmware that would remove the passcode lockout on the phone. Apple has said both publicly and in court filings that it will fight the order as much as possible, and the company has drawn support from many cryptographers, tech companies, and even the husband of a survivor of the attack.

In the new filing, Eileen Decker, a United States Attorney, argued that the court order is "modest" and only applies to a single iPhone. (The technical details about how this order would be confined to one phone are spelled out in detail for the first time in another Thursday filing.)

"The government and the community need to know what is on the terrorist's phone, and the government needs Apple's assistance to find out," she wrote.

In a call with reporters shortly after the government brief was filed, Apple lambasted the government.

"The tone of the brief reads like an indictment," Bruce Sewell, Apple's general counsel said. "In 30 years of practice I don't think I've ever seen a brief that was intended to smear."

"It has thrown all decorum to the winds," he added.

In later pages, Decker added that the government has full confidence in Apple's ability to keep this new iOS—which Apple has dubbed "GovtOS"—a secret.

Next, contrary to Apple's stated fears, there is no reason to think that the code Apple writes in compliance with the Order will ever leave Apple's possession. Nothing in the Order requires Apple to provide that code to the government or to explain to the government how it works. And Apple has shown it is amply capable of protecting code that could compromise its security. For example, Apple currently protects (1) the source code to iOS and other core Apple software and (2) Apple's electronic signature, which as described above allows software to be run on Apple hardware. (Hanna Decl. Ex. DD at 62-64 (code and signature are "the most confidential trade secrets [Apple] has").) Those—which the government has not requested—are the keys to the kingdom. If Apple can guard them, it can guard this.

The government also accurately points to a crucial fact in its favor: that Apple has already handed over data concerning 4,000 iPhones to Chinese authorities and that the company accommodated government demands to put Chinese iCloud users' data physically in China.

Such accommodations provide Apple with access to a huge, and growing, market. (Wilkison Decl. Ex. 12.) This Court's Order changes neither the carrots nor the sticks that foreign governments can use on Apple. Thus, it does not follow that if America forgoes Apple's assistance in this terrorism investigation, Apple will refuse to comply with the demands of foreign governments. Nor does it follow that if the Court stands by its Order, Apple must yield to foreign demands, made in different circumstances without the safeguards of American law. Lawful process in America cannot be confined by potential lawless oppression elsewhere merely because a corporation chooses to manufacture and market its products globally, without regard to its host countries' legal regimes. … If Apple can provide data from thousands of iPhones and Apple users to China and other countries, it can comply with the AWA in America.

Sewell called these references to China "ridiculous," insinuating a "sinister relation with China."

"We add security features to protect our customers from hackers and criminals—to suggest otherwise is demeaning," he added.

Apple attorneys on the call, who were granted anonymity, pointed out that iCloud data in China is encrypted and Chinese authorities do not have access to it, except through an American legal process. They added that the Chinese Wi-Fi standard known as WAPI was a "trade issue," and not a security issue.

An argument in three acts

Last month, Apple put forward its own legal arguments, based on a rejection of a 1977 Supreme Court decision , the prominent case that relies on the All Writs Act in which the authorities were demanding the utility to implement a pen register trap and trace device. Apple also argued that the government's interpretation of the All Writs Act goes too far, fails the previous Supreme Court three-part test, and violates Apple's First and Fifth Amendment rights.

On Thursday, the Department of Justice attacked each of Apple's arguments head-on, and it also spent some time pointing out that the botched password change that made an attempted iCloud backup unworkable is irrelevant.

The opening section of the government's brief is devoted largely to defending the legitimacy of the All Writs Act itself—going so far as to essentially mock Apple's characterization of the law as "dusty and forgotten." After several pages of arguing the legitimacy of the AWA itself, the DOJ again turns back to New York Telephone's "three factor" test. Those factors include the company's distance, or "remove" from the case; whether the government's request places an "undue burden" on Apple; and whether the company's assistance was "necessary."

The government again re-iterated its belief that Apple is not "far removed from the underlying controversy."

Apple argued previously that by putting the phone into the "stream of commerce," it maintained no interest in the phone. Unlike the case of New York Telephone, which was a government-regulated public utility, Apple was entirely separate.

But the DOJ doesn't buy that line of reasoning:

Moreover, Apple maintains a continued connection to its phones well beyond their sale, and has deliberately developed its phones so that Apple alone holds the means for courts' search warrants to be carried out. As Apple's business model and it's representations to its investors and customers make clear, Apple intentionally and for commercial advantage retains exclusive control over the software that can be used on iPhones, giving it monopoly-like control over the means of distributing software to the phones. As detailed below, Apple does so by: (1) firmly controlling iPhones' operating systems and first-party software; (2) carefully managing and vetting third-party software before authenticating it for use on iPhones; and (3) continually receiving information from devices running its licensed software and its proprietary services, and retaining continued access to data from those devices about how its customers are using them. Having established suzerainty over its users' phones—and control over the precise features of the phones necessary for unlocking them—Apple cannot now pretend to be a bystander, watching this investigation from afar. … Rather, Apple is intimately close to the barriers on Farook's locked iPhone because Apple specifically designed the iPhone to create those barriers.

The government then addresses a question of burden.

Prosecutors note that Apple is "one of the richest and tech-savviest companies in the world, and it is more than able to comply with the AWA order." Apple, the government observes, earns more revenue than the annual budget of California.

"Indeed, Apple's revenues exceed the nominal GDPs of two thirds of the world's nations," Decker wrote. "To build the ordered software, no more than ten employees would be required to work for no more than four weeks, perhaps as little as two weeks."

But beyond the sheer financial burden, the DOJ also tackles Apple's question of burden as it pertains to writing code itself. The government spends considerable time referring back to a 1980 case that appeared before the 9th Circuit Court of Appeals, also involving the government-forced used of a pen register on a telecom. In that case, known as Mountain Bell, the court held that "The principles announced in New York Telephone compel the same result here."

Specifically, the court was justified in authorizing Mountain Bell to program "a control computer to 'trap' incoming calls to the designated telephone number."

The question of burdensome is "nonsensical," according to Fred Cate, a law professor at Indiana University.

"We don’t measure the impact of privacy and security intrusions by how much effort they take, but rather by what their effects are," he told Ars. "So if the government ordered a maintenance worker to open a spillway in a dam that results in flooding a city, we don’t say it was okay because the worker just had to turn one lever."

The government also makes a point of referencing the 1807 treason trial of Vice President Aaron Burr, noting that an appellate court did compel Burr's assistant to decrypt a cipher used by his employer.

With respect to the question of necessity, the government quickly dispenses of that, saying that New York Telephone doesn't create an "absolute necessity" standard—so enlisting the assistance of another government agency, such as the National Security Agency, is not needed in the government's view.

In the call with reporters, Apple attorneys underscored that the company works with federal law enforcement on a daily basis, saying that those agents are well-meaning, intelligent, and crucial to the country.

Do you still have First Amendment rights if your speech is private?

The government also attacks Apple's arguments that its Constitutional rights are being violated.

Apple's claim is particularly weak because it does not involve a person being compelled to speak publicly, but a for-profit corporation being asked to modify commercial software that will be seen only by Apple. There is reason to doubt that functional programming is even entitled to traditional speech protections.

In short, because the words that Apple is being compelled to say won't be seen publicly, the free speech issue is moot.

On a call with reporters, Apple attorneys countered that even if you write private poetry, your First Amendment rights still stand.

Towards the very end of the brief, prosecutors simply wave away any Fifth Amendment questions, saying "it is ludicrous to describe the government's actions here as 'arbitrary.'"

With respect to the entire iCloud debacle—where it was revealed earlier that San Bernardino County officials changed the iCloud password at the behest of the FBI, making an attempted forced iCloud backup impossible—the government says this doesn't matter. (This is also apparently in contrast to what FBI Director James Comey said recently before Congress, that the FBI did err in its request to change the password.)

As the prosecutor, Eileen Decker, continued:

For several reasons, a forced iCloud backup would not have been successful even if the password had remained unchanged. Farook's iPhone was found powered off. (Supp. Pluhar Decl. ¶ 2.) Subsequent testing has revealed that once powered off, an iPhone will not back itself up to an iCloud account unless and until it has been unlocked at least once by use of the passcode. (Perino Decl. ¶¶ 6.d, 37-39.) Moreover, the evidence on Farook's iCloud account suggests that he had already changed his iCloud password himself on October 22, 2015—shortly after the last backup—and that the auto-backup feature was disabled. (Pluhar Decl. ¶ 8; Supp. Pluhar Decl. ¶ 9.) A forced backup of Farook's iPhone was never going to be successful, and the decision to obtain whatever iCloud evidence was immediately available via the password change was the reasoned decision of experienced FBI agents investigating a deadly terrorist conspiracy. Moreover, even if—contrary to how Apple built and designed it—Farook's iPhone could have been forced to sync to Apple's iCloud network, that would not be an adequate substitute to unlocking and searching the phone itself. Both the FBI's testin and Apple's security documentation show that entire categories of evidence—including device-level data such as the "keyboard cache" (which records recent keystrokes)—reside only on the iPhone and not on an iCloud backup, and that some of the backup data would still have been encrypted. (Supp. Pluhar Decl. ¶ 10.) But that data remains on the iPhone. Thus, even with a full set of backups, the government still would have needed to search the phone itself in order to leave no stone unturned in this important investigation.

Cate added that Apple has worked to make its devices more secure over time.

"These are great developments that reflect the critical role that iPhones typically play in their users’ lives, collecting, storing, and transmitting personal, often sensitive, information involving health, finance, political opinions, intimate relationships," he concluded.

"Both the market and security experts have applauded Apple’s efforts to make the iPhone more secure. Now the government is trying to force Apple actively to compromise that security—in effect, to undo the progress on security of the past decade. It doesn’t seem to matter whether we characterize Apple as a 'bystander' or as the manufacturer of the phone and author of its operating system, the government is still demanding the same thing and the impact on users is still the same."

Apple has until March 15 to issue its final reply. The two sides are set to square off in federal court in Riverside, California on March 22. Ars will be present at that hearing.