Unless The Phone Is

That is like saying a ride on horseback is materially indistinguishable from a flight to the moon.  Both are ways of getting from point A to point B, but little else justifies lumping them together.  Modern cell phones, as a category, implicate privacy concerns far beyond those implicated by the search of a cigarette pack, a wallet, or a purse. ...

A cell phone search would typically expose to the government far more than the most exhaustive search of a house: A phone not only contains in digital form many sensitive records previously found in the home; it also contains a broad array of private information never found in a home in any form -- unless the phone is.

-- US Supreme Court Chief Justice John Roberts, writing for the majority in a ruling that a search of an arrestee's cellphone requires a warrant, 25 June 2014