I think it should only be allowed WITH a warrant.
The Founding Fathers knew what they were doing, as always they hit a good balance: yes, sometimes it will be necessary for the state, in self preservation, to intrude to the greatest degree- but ONLY when the reason it needs to do so and the basis it has for the belief that doing so will yield usable and pertinent data is supported by facts and examined by a judge (and ideally any interested party).
Wiretapping, reading mail, breaking a phone - if the government cannot clearly state why and what well enough that you and I would agree with it then hell no. If they can then such is a necessary thing. It’s really just common sense that was perfectly well understood 200 years before such a thing as an iPhone.
Carrier pigeon or pony express.. The message . and the motive of the message sender remain the same. Matters not.
Technologies may change.. Agendas don’t.
To my understanding Apple sold the phones to the public as having unbreakable encryption, even to Apple. So the state is now ordering that Apple must help them find out what is on the phone, and possibly any other phones? Maybe Apple should just say yes, but only if the state makes a one time payment to defray the cost of the loss of consumer confidence in Apple products, like 200 billion or so.
Freegards
Apple’s position (and I’m not sure I agree with it) is, once they create the exploit (a copy of iOS 9 that breaks encryption) that it will inevitably get into the wild and ruin their business model.
If Apple writes the code and installs it on THIS phone, then destroys the code base and the FBI destroys the phone after they get the data, I don’t know that that’s a problem.
And yes, I agree they should demand a warrant.