Illegal searching?

what do the police need to search your automobile? in this case we were in oregon and had told the officers several times that they were not welcome to search the car. they had no warrant. thank you.

Generally they need probable cause to search your car. If, for example, they smelled marijuana smoke or saw a crack pipe in the car when they stopped you for a traffic violation, they can search your car. Also, if they are arresting you, for example for drunk driving, they can search your car. If they have reliable information that you are carrying contraband in your car, they can stop your car and search it. You need to give more facts.