Uh, yes. If the guy was arrested for a crime, why not? If they arrest somebody, can’t they search his car without a warrant?
See Arizona v. Gant (2009).
The court limited the regularly abused “search incident to arrest” which was originally carved out as an exception to the warrant requirement to prevent the destruction of evidence or officer safety.
But the cops were arresting people for minor traffic violations or outstanding warrants for failure to pay tickets, etc. then searching everything in the car while the person is handcuffed in the back seat of the police car.
Scalia griped about the abuse of search incident (since the cops expanded it to situations where the rationale for the rule wasn’t implicated) since the late 80s. He was exactly right, and finally got a 5-4 majority in the above referenced case.
Now the facts must implicate the original basis for search incident to arrest, or the search must be an offense related search.
So, if one is arrested for running a stop sign and placed in the back of the patrol car, the cops can’t search everything in the car pursuant to the arrest.
It’s hard to imagine many stops where the contents of the phone should be subject to a warrantless search.
Either way, if I thought they might confiscate my phone I would probably go to settings and reset (erase) my phone.
I could always restore it later at home- that is if they gave me the phone back.