All of the talking heads are working in overdrive, and politicians are lining up to take sides on the issue. I've heard just about every argument imaginable on the subject of privacy, and whether or not the FBI should have the right to decrypt the phone. The answer to that, for the curious, is "yes." In particular, "yes, they have a valid court order."
Unfortunately, that question (and the answer) is also totally f***ing irrelevant. Some people might then say, "oh, well, the real question is whether Apple should have to 'help' the FBI decrypt the phone." That is a bit closer, but it still misses the heart of the issue.
At issue here is not encryption, or Apple's track record of helping the FBI (which they do have), or even whether or not "unbreakable" encryption should be lawful, but a decades-old battle over one of the most sacred rights that We the People are afforded by the United States Constitution.
The real issue here is the powers of court order and legislation over the protections of the First Amendment.
At issue here is the Freedom of Speech. See, the US Supreme Court has found time and time again that the First Amendment not only allows people freedom of speech, but allows them the freedom to refrain from speaking. That last bit is central to the current debate, so bear it in mind for the rest of this post, please.
As we know, the former part (the ability to speak) can be suspended in certain situations- the Supreme Court has upheld gag orders, for example, as necessary to protect due process- but the second part has heretofore typically been considered sacrosanct. That is to say, for a long time, SCOTUS has upheld the idea that the First Amendment also protects people from being compelled to speak. Certain exception do exist, including, for example, a purveyor of goods being required to provide factual information about those goods, provided that the provision of the information is not unduly burdensome; think, for example, of nutritional labeling on food packaging.
Now, where does freedom of speech (or lack thereof) come in to to play, here? We're talking about software, right? Well, Apple is expected to assert that code, and in particular its cryptographic signature delivered to iPhones with every OS update and app, should be considered speech. The reasoning here is that the signature allowing software to be installed on iOS devices constitutes an endorsement of that software. If that seems a bit far-fetched, it's worth nothing that there's already precedent for treating computer code as free speech; see Bernstein v. U.S. Department of Justice (1999).
Apple has argued, and will likely continue to argue, that they are being not only compelled to speech, which would be bad enough, but compelled to burdensome speech, i.e. tasking their internal personnel and resources to create something which does not currently exist, at potentially significant monetary cost, but then further "endorsing" that software by signing it, which carries the risk of very real damage to their reputation.
The various three-letter agencies of the U.S. federal government are hoping to get a court order supporting the idea that computer code is not protected speech.
This would, among other things, allow the Department of Justice to begin regulating computer programs as "arms" under ITAR again, thereby allowing it to be heavily export-controlled as it was from the Red Scare until the mid-90s*. The most frightening implication, however, is that it would open the door to web content potentially no longer be considered protected speech. Yes, you read that correctly- web content is invariably stored as some sort of code or markup, and it's a very short ride from "computer programs are not protected speech" to e.g. "HTML markup is not protected speech." Goodbye, warrant canaries (a goal of the fed for some time now anyway). This is not some new problem of the twenty-first century, nor is this about terrorism, or gun control, or human lives- this is just the latest play in an attempt by the U.S. federal government to whittle and chip away at the First Amendment. They've been trying to do this very thing for at least thirty years. It's also worth noting that there are dissenters on this idea, who think that Apple's argument is a non-starter. To that, all I can say is, "we'll have to wait and see."
That's why it's so important for Apple, and other tech companies, to fight this all of the way to SCOTUS, if necessary. A SCOTUS ruling supporting the idea that computer code is not protected speech, which is a very real possibility, would open a Pandora's box of new federal government powers in this twenty-first century, where technology is everywhere.
It's a very short ride from computer code not being considered protected speech, to the federal government being able to compel people to provide passwords, surrender private encryption keys, or even write entire programs for free.
* Note that cryptographic software was explicitly removed from ITAR circa 1996 strictly as a legal maneuver to prevent a judgement from being issued in an ongoing case; Bernstein v. DoJ (1999) later invalidated the use of ITAR for computer code, but the ruling was by then moot anyway. Until now.