The legal tug-of-war over whether or not Apple can be forced to unlock a secure iPhone continued last night, with the U.S. Justice Department filing a sharp rebuke to Apple’s claims that it can’t legally be compelled to rewrite its software, and with Apple responding by accusing federal prosecutors of operating a “smear” campaign through the court system.

Last month, a federal judge ordered Apple to aid the FBI in unlocking an iPhone found in the car of one of the terrorists who massacred 14 people in San Bernardino, CA, on Dec. 2, 2015. The order was granted under a statute known as the All Writs Act, which allows a judge to compel a person or group to assist enforcing a court order — but only if that assistance is both necessary and “agreeable to the usages and principles of law.”

The iPhone’s built-in security system only allows a limited number of attempts at unlocking the device before running the risk of losing the data that the FBI is hoping to find. The most likely way around this concern would be for Apple to rewrite its software and push out an update to the phone, removing the limit on unlocking attempts.

On Feb. 25, Apple filed a motion to vacate [PDF] that order, arguing that there is no precedent for this sort of action, and that being compelled to create a backdoor to bypass iPhone encryption has the negative effect of “making its users’ most confidential and personal information vulnerable to hackers, identity thieves, hostile foreign agents, and unwarranted government surveillance.”

Additionally, supporters of Apple’s position on the matter contend that compelling the company to rewrite its code is a violation of its employees’ constitutional rights by forcing them to “repudiate” their “belief regarding… the value of their customer’s privacy and security.”

“In other contexts, compelled speech and affirmations of belief that substantially hinder the speaker’s ability to communicate its desired message are clearly unconstitutional,” explains a supporting brief [PDF] filed by dozens of experts in the fields of computer science and encryption.

But yesterday, in its response brief [PDF], the DOJ argues that there is no “unreasonable” burden on Apple, pointing out that the company would only “need to set aside as few as six of its 100,000 employees for perhaps as little as two weeks,” and that the order “allows Apple to decide the least burdensome means of complying.”

“As Apple well knows, the Order does not compel it to unlock other iPhones or to give the government a universal ‘master key’ or ‘back door,'” reads the filing, which notes that the phone itself belongs to San Bernardino County, where shooter Syed Rizwan Farook was employed. Because, as part of his employment, he’d previously consented to making his phone available to be searched, the government contends that there is no Fourth Amendment issue.

Though it should be noted that Apple is not challenging the FBI’s authority to search the phone. Instead, the company maintains that it can’t be compelled to assist in that search. Additionally, while the government repeatedly insists that the order applies only to this phone, Apple has pointed out in previous filings that there are currently multiple legal attempts to compel the company to aid in unlocking devices.

“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,” continues the DOJ, which goes on to slam the company, saying, “Apple’s rhetoric is not only false, but also corrosive of the very institutions that are best able to safeguard our liberty and our rights: the courts, the Fourth Amendment, longstanding precedent and venerable laws, and the democratically elected branches of government.”

The DOJ argues that bigger-picture concerns about privacy and network security are a “diversion,” and that conscripting Apple into aiding the FBI is “not lawless tyranny,” but rather, “it is ordered liberty vindicating the rule of law.”

Speaking to the media to discuss the DOJ response, Apple general counsel Bruce Sewell called the government’s argument, “an unsubstantiated effort to vilify Apple,” a “cheap shot” and “an act of desperation.”

“In my 30 years I’ve never seen a legal brief more intended to smear the other side with false innuendo,” said Sewell.

In the middle of the legal battle in California, a federal judge in a similar case in New York recently ruled that the All Writs Act does not give the government the authority to force Apple to assist the FBI.

The judge in that case concluded that even if the Act did apply, Apple was too far removed from the criminal conduct involved, and that the company would be unduly burdened by the requirements of such an order.

However, the government argues in its response in the California case that legal precedent shows that the All Writs Act is intended to be a fluid piece of legislation that evolves to cover new technologies.

The DOJ points to the 1977 Supreme Court ruling in United States v. New York Telephone Co., in which SCOTUS narrowly held that the All Writs Act could be used to force telephone companies to install pen registers — devices that track all numbers called from a particular phone number — if that phone company is “in a position to frustrate the implementation of a court order or the proper administration of justice.”

The government points out that, 40 years ago, the company unsuccessfully made arguments similar to the ones being made by Apple now: “that Congress had not given courts the power to issue such an order in its prior legislation; that the AWA could not be read so broadly; that it was for Congress to decide whether to provide such authority; and that relying on the AWA was a dangerous step down a slippery slope ending in arbitrary police powers.”

The DOJ also makes the point that in 2014, SCOTUS held that police can not search a phone’s contents without a warrant.

“Thus, Apple’s privacy questions, far from being unanswerable by any court, have already been answered by the Supreme Court, and the government complied… by obtaining a warrant here,” writes the DOJ, again potentially glossing over the fact that a warrant to search a phone does not mean that the phone will unlock itself.

Regardless of how the court rules on Apple’s motion to vacate the order, the matter seems destined to ultimately be decided by a federal appeals court or by SCOTUS.

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