The tech is way ahead of the law. And the court only has a few months to make a ruling - a ruling which I bet will get amended as laws and precedents start being created.
Via SCOTUSblog, some suggested reading:
"But, as the discussion went on, it seemed that there were two lines that would have to be drawn: one, to define the kind of cellphone contents that were so private that they would be insulated from search; and, second, to define the limits of a search warrant so that the police stayed away from what was private.
The Justices seemed well aware that, even if they somehow were able to craft some Fourth Amendment limitations on searching cellphones, they still would have real difficulty in implementing those limits by telling a magistrate how to write a search warrant to guide the police. “A warrant for what?” Justices Ruth Bader Ginsburg and Antonin Scalia both asked. “What would police have to show [to get a warrant]?” Ginsburg added. 'Although there was a lot of talk about how to figure out what most cellphone users believed should be private among the contents on their devices, there did seem to be a rough consensus that they do believe that, to some hard-to-define degree."
"Going into the oral argument, both California and the federal government told the Court that, whenever police make an arrest, cellphones should be fair game for a search for all of the same reasons that police can search, for example, the arrestee’s wallet without a warrant. But it’s hard to see five Justices voting in support of that rule, given the widespread skepticism that the argument met on the Court. Justice Elena Kagan was one of the most vocal opponents of such a rule, telling California Solicitor General Edward DuMont that, following his logic, an arrest for a minor offense like driving without a seatbelt would allow police to look at every single e-mail on the arrestee’s phone, along with his bank records, medical data, calendar, and GPS data. That, she suggested, “strikes me as a very different kind of world” from looking at someone’s billfold, given that “people carry their entire lives on cellphones.” Justice Antonin Scalia later echoed this idea, calling it “absurd” that police should be able to search someone’s iPhone for that kind of minor offense. Justice Anthony Kennedy, whom many often regard as a key vote on the Court, expressed concerns as well, telling Deputy U.S. Solicitor General Michael Dreeben (who argued on behalf of the federal government in both cases today) that “we are living in a new world,” in which someone arrested for a minor crime has her “whole life on [her] phone” and asking whether Dreeben could suggest some limits on the potentially broad sweep of the government’s rule.
'But even if California and the federal government seem unlikely to win outright, the chances that the Court will require police officers to get a warrant whenever they want to search an arrestee’s phone appear even slimmer.