The Fourth Amendment expressly imposes two requirements:All searches and seizures must be reasonable; and a warrant may notbe issued unless probable cause is properly established and the scope of the authorized search is set out with particularity. Although“ ‘searches and seizures inside a home without a warrant are pre-sumptively unreasonable,’ ” Brigham City v. Stuart, 547 U. S. 398, 403, this presumption may be overcome when “ ‘the exigencies of the situation’ make the needs of law enforcement so compelling that [a]warrantless search is objectively reasonable under the Fourth Amendment,”