Define the "exclusionary rule."

The exclusionary rule is fundamentally a legal principle that prohibits the use of illegally obtained evidence in court. This principle is designed to protect individuals' Fourth Amendment rights against unreasonable searches and seizures. The rationale behind the exclusionary rule is to deter law enforcement from conducting unlawful searches or obtaining evidence in violation of a person’s constitutional rights. If evidence is obtained in a way that violates these rights, such as without a warrant or probable cause, it cannot be presented in court during legal proceedings. This ensures that courts consider only evidence that has been lawfully obtained, thereby upholding the integrity of the judicial process and protecting citizens from unconstitutional actions by the state.