Well according to Apple ,they have not;
"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."
Customer Letter - FAQ - Apple
What Apple has done in the past is give law enforcement with a warrant or court order access to iCloud data for that user, but they have never decrypted an iPhone for law enforcement.
On a separate note, I for one stand in support of Apple. I do not believe that American should have to give up liberties for security or the allusion of security. I strongly believe that this is larger than the this one case and this one phone. This will set up a very dangerous precedent. I agree that what those horrible people did was well horrible, but again Apple stance on this isn't about this one case. Apple has already handed over the FBI everything they could, but this is where they draw the line. Do you really believe that if the FBI is successful in forcing Apple to create this dangerous tool, that they would only use it one, because I don't. I mean they're is already a
report out that the DOJ has another 12 iPhone theyre going to force Apple to unlock if Apple looses this case. And than Manhattan D.A. is next on the list. This case, if Apple looses set a very dangerous precedent. (That rant was not directed at bobshine, I just wanted to make my views on this case public)