The point of a warrant is that a person who is not involved and is objective listens to what the policeman is saying, knowing that
sometimes, like me or any other human being, a policeman can get a little carried away. So if, in fact, he does show the warrant, that there is this basis, you issue the warrant. Many, many and if he doesn’t you don’t. It isn’t because they’re difficult legal questions. It’s just you want that third dispassionate mind to review what the facts are.
Justice Breyer, on the importance and purpose of a warrant, US v Wurie, oral argument, April 29, 2014.