Are you talking about the San Bernadino case? The FBI hired a security firm to exploit an old iPhone on iOS 9. They didn't get in through iCloud.Like iMessage where the feds got it despite end-to-end? Guess what? You sync your iMessages to iCloud backup you just opened the door.
But Apple doesn't tell you that. It was found out real world in the courts. Apple marketing speak is typically not full reality.