The Exclusionary Rule prevents evidence obtained in violation of the 4th Amendment from being used in a criminal trial. For example, if police found 10 kilograms of cocaine in a car trunk without a warrant or probable cause, this evidence could not be used to prosecute the driver, even though they were likely involved in drug trafficking. While the rule means some guilty parties may avoid conviction, it protects against violation of individuals' constitutional rights against unreasonable search and seizure.