Yes. With a proper warrant, as a reasonable and therefore constitutional search and seizure. My understanding is that in most states this would mean myself and my possessions can be searched for a DUI but not for a normal traffic stop.
Right of search is, of course, not an unfettered right, as it is only reasonable if the "fetters" of the Constitution are complied with.
Electronic data storage is obviously something the Founders didn't have. But I see no reason why it should be considered to have greater rights to privacy than older forms of record-keeping.
For example, my understanding is that if I'm arrested, legally, for any reason, my wallet and other records I have on my person at the time will be searched, with the information found potentially used against me at trial, perfectly constitutionally.
Cell phones are simply an extension of this. If I don't want evidence used against me, I shouldn't be carrying it around with me.
There are, of course, ways to encrypt this data, and a person can certainly use them legally, just as he would have the right to keep his dead tree journals in code. A person should not be compelled to provide a password, just as he, I assume, cannot be compelled to decode a paper journal if doing so violates his 5A rights.
But the cops have every right to try on their own to break a phone's encryption, just as they do to break a code on paper.
If people choose, for convenience, to carry around with them a device containing evidence that can be used against them, that's their problem, just as if they chose to carry a paper diary with similar information.
That authorities may sometimes cross the bounds of what is constitutionally reasonable does not mean any and all electronic storage should be protected.
The Supreme Court brought the constitutional right of personal privacy into the digital era Wednesday, ruling unanimously that police may not search a smartphone or similar device without a warrant from a judge....Until Wednesday, the court’s long-standing view was that police were free to search someone who was stopped on the street or in his car and put under arrest. Officers could check a suspect’s pockets and examine his possessions, including a wallet, purse and pockets.
The intention was to allow police to protect themselves by finding weapons. But they were also free to collect evidence, such as drugs, stolen goods or papers that might lead to other suspects.
This was known as the “search incident to arrest” rule, and it had been set out in 1973 by then-Justice William H. Rehnquist. A few years later, Roberts came to Washington to be a law clerk for Rehnquist, and in 2005, he succeeded him as chief justice.
In Wednesday’s opinion, Roberts said Rehnquist’s “categorical rule” for allowing the police to freely search “physical objects” did not make sense when those items were electronic devices....