If a defendant freely and voluntarily agrees to a search, the search is valid and whatever the officers find is admissible in evidence. No equivalent to Miranda warnings exists in the search and seizure area. Police officers do not have to warn people that they have a right to refuse consent to a search (U.S. v. Drayton, U.S. Sup. Ct. 2002; Ohio v. Robinette, U.S. Sup.
Police officers do not need a warrant to make a search “incident to an arrest.” After an arrest, police officers have the right to protect themselves by searching for weapons and to protect the legal case against the suspect by searching for evidence that the suspect might try to destroy.