Under the exclusionary rule, evidence collected in violation of the defendantís constitutional right is inadmissible for a criminal prosecution in a court. Exclusionary rule determines the admissibility of evidence in trial based on how it has been obtained instead of what it proves.
Evidence obtained in breach of the provisions of the Bill of Rights for protection from compelled self incrimination or from unreasonable searches and seizures is inadmissible. Confession under duress or torture in police custody is liable to be excluded. Similarly any recovery without adherence to such rights can be thrown out of consideration at the trial.
The exclusionary rule can be applied to protect the rights of any citizen or even alien, whether illegal or documented, residing within the United States.
The exclusionary rule holds good for evidence obtained through unauthorized searches and seizures without a lawful warrant, involuntary confessions, suspect identification in violation of the constitutional rights, wiretapping evidence in breach of federal laws and any other evidence collected in abuse of human rights.
However, the exclusionary rule does not apply in a parole revocation proceeding or in a grand jury trial or in civil proceedings. Moreover, evidence even if unlawfully obtained from the defendant by a private person is admissible in evidence. Further, in the face of overwhelming evidence against the defendant, he cannot turn the case to his advantage by highlighting the instances of police breaching rules against him. Again, where even normal police investigations would have inevitably led to the discovery of the evidence, the same is not excluded in witness action even on the ground of police excesses. Besides evidence obtained in contravention of the defendantís constitutional rights may be admissible if knowledge of the evidence has also been gained from an independent source completely unrelated to the illegality.