Here’s a link to Apple’s original Message to Our Customers.

This FAQ provides more detail on Apple’s position. It is really well written and clearly lays out Apple’s issues with doing what the government asks.

Here’s just a taste, well worth reading the whole thing:

The government asked a court to order Apple to create a unique version of iOS that would bypass security protections on the iPhone Lock screen. It would also add a completely new capability so that passcode tries could be entered electronically.

This has two important and dangerous implications:

First, the government would have us write an entirely new operating system for their use. They are asking Apple to remove security features and add a new ability to the operating system to attack iPhone encryption, allowing a passcode to be input electronically. This would make it easier to unlock an iPhone by “brute force,” trying thousands or millions of combinations with the speed of a modern computer.

There are many ways to build a backdoor. Creating a version of iOS that makes a specific iPhone easier to crack is one way. But, as this cartoon suggests, creating a toolchain that would allow that weakened version of iOS to be injected into any modern iPhone is a much more frightening backdoor. Breaking into a single iPhone is a privacy issue. Forcing Apple to create an iPhone-cracker is a security issue. Both count.

Second, the order would set a legal precedent that would expand the powers of the government and we simply don’t know where that would lead us. Should the government be allowed to order us to create other capabilities for surveillance purposes, such as recording conversations or location tracking? This would set a very dangerous precedent.

Amen. This needs to be reasoned through. We can’t make this decision based on politics.

In response to the question: Has Apple unlocked iPhones for law enforcement in the past?

No.

We regularly receive law enforcement requests for information about our customers and their Apple devices. In fact, we have a dedicated team that responds to these requests 24/7. We also provide guidelines on our website for law enforcement agencies so they know exactly what we are able to access and what legal authority we need to see before we can help them.

For devices running the iPhone operating systems prior to iOS 8 and under a lawful court order, we have extracted data from an iPhone.

And on how Apple has helped the FBI:

We have done everything that’s both within our power and within the law to help in this case. As we’ve said, we have no sympathy for terrorists.

We provided all the information about the phone that we possessed. We also proactively offered advice on obtaining additional information. Even since the government’s order was issued, we are providing further suggestions after learning new information from the Justice Department’s filings.

One of the strongest suggestions we offered was that they pair the phone to a previously joined network, which would allow them to back up the phone and get the data they are now asking for. Unfortunately, we learned that while the attacker’s iPhone was in FBI custody the Apple ID password associated with the phone was changed. Changing this password meant the phone could no longer access iCloud services.

As the government has confirmed, we’ve handed over all the data we have, including a backup of the iPhone in question. But now they have asked us for information we simply do not have.

These are interesting times.