What type of evidence is most affected by the exclusionary rule?

The exclusionary rule is a legal principle that prevents evidence obtained through violations of a defendant's constitutional rights from being used in court. The type of evidence most affected by this rule is illegally obtained evidence. This can include physical evidence that was gathered without a proper warrant, probable cause, or consent, as well as any statements made under coercion or without the appropriate Miranda warnings. When evidence is deemed inadmissible due to the exclusionary rule, it cannot be introduced in a trial, potentially impacting the prosecution's case significantly.

In contrast, other types of evidence, such as witness statements or probation reports, may not face the same challenges regarding admissibility unless they are also linked to a constitutional violation. For example, a witness statement that was obtained lawfully can still be used, regardless of the overall legality of the investigation. Thus, the answer identifies the key focus of the exclusionary rule, which is to protect individuals from unlawful searches and seizures, thereby maintaining the integrity of the judicial system.