That's going to depend on the situation. For instance, if you give an officer consent to search you, then obviously they're allowed to search you. Also, if an officer believes that they have probable cause that you committed a crime, they can search you. They can search you to what's called a search incident to arrest. That's obviously if you are placed under arrest, an officer can then search your person and they can possibly even search the vehicle that you were driving or traveling in. Furthermore, there was a United States Supreme Court case a while back, Terry vs. Ohio, which says what's also known as the stop and frisk law. In certain situations, an officer can stop you and then pat you down to determine if you are carrying any type of weapons.