What does the exclusionary rule pertain to?

The exclusionary rule pertains specifically to evidence obtained illegally. It is a legal principle that prohibits the use of evidence in court if it was acquired in violation of the defendant's constitutional rights, particularly the Fourth Amendment, which protects against unreasonable searches and seizures.

The purpose of the exclusionary rule is to deter law enforcement from conducting unlawful searches and to uphold the integrity of the judicial system. For example, if police obtain evidence through an illegal search—such as without a warrant and without probable cause—such evidence cannot be used against a defendant in court. This rule emphasizes the importance of adhering to legal standards in gathering evidence to ensure fair trials and protect individual rights.

In contrast, confessions made under duress relate to the admissibility of statements made by defendants and may use a different legal framework for evaluation. Witness testimonies can be challenged for reliability or credibility but are not directly affected by the exclusionary rule unless obtained through illegal means. Necessary evidence for conviction does not specifically focus on the legality of how it was obtained but rather on its relevance and sufficiency to support a conviction. Thus, the exclusionary rule is fundamentally linked to the legality of evidence collection, making it a crucial aspect of criminal procedure.