> The fourth amendment just says searches have to be reasonable, not that they have to be done pursuant to a warrant. The only reason it doesn't say that is th

> The fourth amendment just says searches have to be reasonable, not that they have to be done pursuant to a warrant. The only reason it doesn't say that is that it's inherent in the term "warrant". A warrant is exactly the legal authority to use force on behalf of the government contrary to the rights which the law would normally guarantee, which is a prerequisite for performing any search or seizing any property (absent the owner's consent, of course). Any law purporting to authorize searches is a warrant, though not necessarily a constitutional one. There is no such thing as a legal search or seizure without a warrant. There are only unauthorized, and thus illegal, searches and seizures, and unconstitutional warrants. If "reasonableness" were enough on its own—in other words, if obtaining a warrant were not a necessary part of the process of conducting a search—there would never have been any reason to place further restrictions on the issuance of warrants, and the entire second half of the 4th Amendment would be void.