Someone already covered the goes with you everywhere part but it's worth noting that a diary though very personal is something you consciously populate with thoughts that you know one day could very well be read by someone else.
A lot of the things people do on a phone they may not even be aware is leaving history and other information on the device as they use it.
You could argue they they should be better informed, but should they really? Should we expect to forever limit ourselves to only our brain for storing secret information as it's the only place held sacrosanct in the eyes of the law?
I think not. The law should change with the times. The mind/brain is expanding into the electronic world and the protections afforded to our biological brain should be extended in concert.
The law should change with the times only when technological change implicates the rationale of a rule. The rationale of the 5th amendment isn't to have a place for storing secret information. It's the uniquely pursuasive nature of confessions and the incentive to coerce them. Note that when there is no such threat, even being in your brain doesn't stop courts from getting at information. A court can compel a witness to testify, for example, so long as the testimony isn't incriminating.
Phones don't implicate the threat of coerced confessions regardless of what is on them.
But the reason for the police being able to search you in the first place is to investigate crime because of the harm it causes to society. That needs to be balanced against the harm such searches cause.
If the harm caused by searches goes up, what changes to balance that?
You're taking the law as a given and saying that society must bend because the law has been constant for many hundred years.
But that's a bug. Yes, the systems for change are rusty and those in power would rather inflict the wrong laws than allow them to change, but the point in this discussion is more than what can Apple get away with now, but what should they strive for. In that sense, what should the law be to best serve people who feel that Apple is right in creating "unhackable" phones?
A lot of the things people do on a phone they may not even be aware is leaving history and other information on the device as they use it.
You could argue they they should be better informed, but should they really? Should we expect to forever limit ourselves to only our brain for storing secret information as it's the only place held sacrosanct in the eyes of the law?
I think not. The law should change with the times. The mind/brain is expanding into the electronic world and the protections afforded to our biological brain should be extended in concert.