I was hoping it would go this way, and pleasantly surprised it was a unanimous decision.
In their comment about the police trying to access information before it is destroyed, I could see a need to start creating laws to allow freezes on peoples accounts (facebook, twitter, voice messages, etc). I.e., the person still has access but can’t delete anything for 48 hours, while the police are seeking a warrant.
Glad it was unanimous as well
The NSA has all that data on its servers anyway. 
Frankly, I wish they’d gone a bit farther and receded from the “search incident to arrest” doctrine slightly. But this will do.
Are the built in security features of modern smartphones sufficient to prevent unwanted intrusion, even by police with a warrant? Can a person be compelled to reveal a password beyond being held in contempt?
This would be similar to a safe combination, but with a physical safe they can always be defeated with time.
A phone’s security can always be defeated with time, too. Except possibly by PDs that are out in the sticks and have limited technical capabilities.
The opinion contemplates remote deletion of data, and says that this is uncommon, and even if it were, that it could be prevented by isolating the device from remote signals. I imagine some kind of Faraday box.
Then, I think you can have something like a dead man’s switch on your phone - if you don’t enter something based on some cadence it automatically erases everything that is sensitive. This can be done without remove activation. You could defeat battery removal with a built in backup that is impossible to remove just for this purpose.
Sure. But allowing warrantless searches of everyone’s phone to defeat technology that might be available to .1% of criminal suspects is overdoing it a bit.
The interesting question is what the ruling portends for similar, but not quite identical, questions raised by electronic surveillance.
It would probably be simpler to just encrypt everything – someone with physical access to the phone could still get the data but couldn’t interpret it without your cooperation.
Alito filed a separate opinion - concurring in part and in the judgement. As far as I can tell, he wanted to let everyone know that he doesn’t like giving this protection to cell phone data, but that he can’t figure out a better solution, and that he looks forward to endorsing legislation that finds a better excuse to expand police power in this way.
Oh - I’m totally against the warrantless search and agree with the ruling. Just thinking of how things could change in the future.
Much of the data “on our phone” isn’t on our phone, and that shall become the case to an even greater extent with time. So while I thought of this suggestion, I don’t think it will be very useful.