Wong Sun v. United States
Citation and Court
371 U.S. 471 (1963) — Supreme Court of the United States
Facts
Federal agents illegally arrested Toy, who made statements implicating Wong Sun. Wong Sun was then arrested without probable cause. Several days later, after his arraignment and release, Wong Sun voluntarily returned to the police station and made incriminating statements. The government sought to use all of this evidence at trial.
Issue
What is the scope of the “fruit of the poisonous tree” doctrine — specifically, which evidence derived from an illegal arrest must be suppressed?
Holding
Evidence must be suppressed if it was obtained as a direct result of a constitutional violation, unless it was derived through means sufficiently attenuated from the illegality. Toy’s statements were suppressed; Wong Sun’s later voluntary statements were not, because they were sufficiently attenuated from his illegal arrest.
Rule / Doctrine
The fruit of the poisonous tree doctrine requires suppression of evidence that is the product of, or comes at by exploitation of, a prior constitutional violation. The test is not simply but-for causation: evidence may be admissible if (1) the connection between the illegality and the evidence is sufficiently attenuated, (2) the evidence was discovered from an independent source, or (3) the evidence would inevitably have been discovered. Wong Sun’s voluntary return to make statements broke the causal chain.
Significance
The foundational case articulating the fruit of the poisonous tree doctrine as a test of exploitation rather than mere but-for causation, establishing the attenuation, independent source, and inevitable discovery exceptions that courts continue to apply.