Which doctrine allows courts to exclude evidence obtained illegally by law enforcement?

The doctrine that allows courts to exclude evidence obtained illegally by law enforcement is known as the exclusionary rule. This legal principle is designed to protect individuals' rights by ensuring that evidence obtained in violation of the Fourth Amendment, which guards against unreasonable searches and seizures, cannot be used in court.

The exclusionary rule was established to deter law enforcement from conducting illegal searches and to uphold the integrity of the judicial process. If evidence is gathered through improper procedures—such as without a warrant or probable cause—it is considered tainted and is therefore inadmissible in a court of law.

While "fruit of the poisonous tree" relates to this doctrine by stating that any evidence derived from illegally obtained evidence is also inadmissible, it is a principle under the broader umbrella of the exclusionary rule. This means that although "fruit of the poisonous tree" is closely associated, it is technically a subcategory of the exclusionary rule rather than the fundamental concept itself.

Understanding the exclusionary rule is crucial for recognizing how legal systems work to protect individual rights and prevent the misuse of governmental authority in the investigation of crimes. It underscores the importance of adhering to constitutional protocols during law enforcement operations.