If you arrest someone, you can totally search him/her for weapons on his/her person or within his/her reach. If you arrest someone in their car, you can search the whole car, pretty much. (The law is still unclear on this point, the Supreme Court keeps waffling on whether the trunk is okay, or just the passenger area, it's really a mess of an area of law). You usually can't search a wallet, unless you have some good reason to believe a weapon can be in there. Cops just generally claim 'razor blades!' and thus get
Carte Blanche to search everything on the suspect's person.
A cop actually doesn't need to affect an arrest in order to 'pat someone down.' If a cop has reasonable suspicion (which is a lower threshold than probable cause, which isn't that high to begin with) that a person is armed and dangerous after engaging them in a conversation, they can request to do a Terry stop pat down. They cop can pat the person down for weapons, but cannot search anything that is clearly not a weapon.
Rac (Who swears this knowledge comes from Crim. class and working in the District Attorney's office, and not from watching Law & Order
)
