"The purpose of a warrant is to allow a neutral judicial officer to assess whether the police have probable cause to make an arrest or conduct a search. As we have often explained, the placement of this checkpoint between the Government and the citizen implicitly acknowledges that an 'officer engaged in the often competitive enterprise of ferreting out crime,' may lack sufficient objectivity to weigh correctly the strength of the evidence supporting the contemplated action against the individual's interests in protecting his own liberty and the privacy of his home."
"[W]hile an arrest warrant and a search warrant both serve to subject the probable-cause determination of the police to judicial review, the interests protected by the two warrants differ. An arrest warrant is issued by a magistrate upon a showing that probable cause exists to believe that the subject of the warrant has committed an offense and thus the warrant primarily serves to protect an individual from an unreasonable seizure. A search warrant, in contrast is issued upon a showing of probable cause to believe that the legitimate object of a search is located in a particular place, and therefore safeguards an individual's interest in the privacy of his home and possessions against the unjustified intrusion of the police."