Amendment IV:

"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."

The police needs a warrant to invade your privacy unless there is reasonable suspicion. If the police presents a warrant they are only allowed to search the area stated on the warrant. If you are pulled over in a traffic stop keep in mind that you are liable to get search if the police have a reason to also keep in mind students are liable for search as well in school buildings.

 This picture is to show an example of what a search warrant could look like for one who has never seen one. Although they vary from state to state they should have a judge name on them, what they are looking for and where they have the permission to search.  Not saying all cops are crooked but officers may at times try to show something that is not a search warrant just to get in to find something. The video is an example of a case that had to do with the fourth amendment as well and demonstrates what should take place in order for the police to search.