This article addresses the admissibility of illegally obtained evidence, as a matter of evidence law, in criminal trials in India. The United States Constitution’s Fourth Amendment jurisprudence provides, as a matter of constitutional law, that illegally obtained evidence is inadmissible. This rule is known around the world as the Exclusionary Rule. The U.S. Supreme Court has carved our several exceptions to the Exclusionary Rule; however, illegally obtained evidence remains inadmissible in criminal trials in the U.S. in most instances. Relevant legal propositions to this effect have been codified under the Police and Criminal Evidence Act of 1984 in the United Kingdom where inadmissibility of illegally or unfairly obtained evidence remains largely a matter of discretion with the trial judge. Under Indian law, there is no statutory prohibition against illegally obtained evidence under either the Indian Evidence Act of 1872 or the Code of Criminal Procedure of 1973. However, a review of reported Indian Supreme Court opinions on the point discloses the existence of a judge made doctrine, largely derived out of British common law, whereby illegally obtained evidence can be excluded at the discretion of the trial judge if the admission of the same would operate unfairly against the accused. This rule is designated as the Unfair Operation Principle.