4th Amendment- the right of the people to be secure in these people, 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 searched , person or things.
2 Court Cases- Terry vs. Ohio, Florida vs. Bostick.
No warrant is required for searches incident to lawful arrest. If a police officer has made a lawful arrest, with or without a warrant, the Fourth Amendment permits the officer to conduct a search of the suspect's person, clothing, and all of the areas within the suspect's immediate reach.