Exclusionary Rule Fruit of the Poisonous Tree
The United States Supreme Court held that the exclusionary rule applies not only to the illegally obtained evidence itself, but also to other incriminating evidence derived from the primary evidence. Id. at 391-92.
The Court extended the exclusionary rule in Wong Sun v. United States to evidence that is the indirect product or fruit of unlawful police conduct. 371 U.S. 471, 487-88, 83 S. Ct. 407, 9 L. Ed. 2d 441 (1963).
Although Silverthorne and Wong Sun involved Fourth Amendment violations, the United States Supreme Court also applied the fruit of the poisonous tree doctrine to Fifth Amendment violations, see e.g., Murphy v. Waterfront Comm'n of New York Harbor, 378 U.S. 52, 79, 84 S. Ct. 1594, 12 L. Ed. 2d 678 (1964), and Sixth Amendment violations, see e.g., United States v. Wade, 388 U.S. 218, 239-42, 87 S. Ct. 1926, 18 L. Ed. 2d 1149 (1967).
"The core rationale consistently advanced . . . for extending the exclusionary rule to evidence that is the fruit of unlawful police conduct has been that this admittedly drastic and socially costly course is needed to deter police from violations of constitutional and statutory protections." Nix v. Williams, 467 U.S. 431, 442-43, 104 S. Ct. 2501, 81 L. Ed. 2d 377 (1984).
The fruit of the poisonous tree doctrine is not without exceptions.
One such exception is the inevitable discovery rule, which allows for the admission of tainted evidence when the prosecution can show by a preponderance of the evidence that its discovery by lawful means was inevitable. Commonwealth v. Pua, 2006 MP 19 P 25, 7 N. Mar. I. 350 (citing Nix, 467 U.S. at 443-44).
"The purpose of the inevitable discovery rule is to block setting aside convictions that would have been obtained without police misconduct." Nix, 467 U.S. at 444 n.4.