Wong Sun v. United States: Supreme Court Case, Arguments, Impact

The case that established the "fruit of the poisonous tree" doctrine

Evidence in a courtroom

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In Wong Sun v. United States (1963), the Supreme Court ruled that evidence uncovered and seized during an illegal arrest could not be used in court. The Court found that even verbal statements made during an unlawful arrest could not be entered into evidence.

Fast Facts: Wong Sun v. United States

  • Case Argued: March 30, 1962; April 2, 1962
  • Decision Issued: January 14, 1963
  • Petitioners: Wong Sun and James Wah Toy
  • Respondent: United States
  • Key Questions: Were Wong Sun and James Wah Toy’s arrests lawful, and were their unsigned statements admissible as evidence?
  • Majority Decision: Justices Warren, Black, Douglas, Brennan, and Goldberg
  • Dissenting: Justices Clark, Harlan, Stewart, and White
  • Ruling: The Supreme Court held that without probable cause, the arrests were not legal. Evidence found during the subsequent illegal search was deemed inadmissible, as were the unsigned statements of the petitioners.

Facts of the Case

Around 6 a.m. on June 4, 1959, a federal narcotics agent knocked on the door of James Wah Toy's laundromat and home. The agent told Toy that he was interested in Toy's laundry services. Toy opened the door to tell the agent that the laundromat did not open until 8 am. The agent took out his badge before Toy closed the door and identified himself as a federal narcotics agent.

Toy slammed the door and took off running down the hall into his home. Agents broke down the door, searched Toy's home, and placed him under arrest. They did not find any narcotics in the house. Toy insisted that he was not selling narcotics but knew who did. He knew of a house on Eleventh Avenue where a man named "Johnny" sold narcotics.

The agents then paid a visit to Johnny. They entered Johnny Yee's bedroom and convinced him to surrender multiple tubes of heroin. Yee said Toy and another man called Sea Dog had originally sold him the drugs.

Agents questioned Toy about the matter and Toy admitted that "Sea Dog" was a man named Wong Sun. He rode along with agents to identify Sun's house. Agents arrested Wong Sun and searched his home. They found no evidence of narcotics.

Over the next few days, Toy, Yee, and Wong Sun were arraigned and released on their own recognizance. A federal narcotics agent questioned each of them and prepared written statements based on notes from their interviews. Toy, Wong Sun, and Yee refused to sign the prepared statements.

At trial, the district court admitted the following pieces of evidence, despite attorney objections that they were "fruits of illegal entry":

  1. Toy's oral statements in his bedroom at the time of his arrest;
  2. The heroin that Johnny Yee gave to agents at the time of his arrest; and
  3. Unsigned pretrial statements from Toy and Wong Sun.

The Ninth Circuit Court of Appeals reviewed the case. The appeals court found that agents did not have probable cause to arrest Toy or Wong Sun, but the items that were "fruits of illegal entry" were properly entered as evidence at trial.

The Supreme Court took on the case, delivering individual findings for Wong Sun and Toy.

Constitutional Issues

Can courts lawfully admit "fruits of illegal entry"? Can evidence uncovered during an arrest that lacks probable cause be used against someone in court?


The attorney representing Wong Sun and Toy argued that agents had illegally arrested the men. The "fruits" of those illegal arrests (the evidence seized) should not be allowed in court, according to the attorney. He further argued that Toy's statements made to the police at the time of his arrest should be covered under the exclusionary rule.

Attorneys on behalf of the government argued that the narcotics agents had sufficient probable cause to arrest both Wong Sun and Toy. When Toy spoke to narcotics agents in his bedroom, he did so out of his own free will, making the statements admissible regardless of whether the arrest was legal.

Majority Opinion

In a 5-4 decision delivered by Justice William J. Brennan, the court excluded all evidence related to Toy's arrest, but ruled that certain evidence could be used against Wong Sun.

The Arrest of Toy and Wong Sun: The majority agreed with the court of appeals that both arrests lacked sufficient probable cause. A judge would not have granted the narcotics agents an arrest warrant based on the evidence they had when arresting Toy, according to the majority. The majority also agreed that the agent at Toy's door misrepresented himself and Toy's decision to run down the hall could not be used as suspicion of guilt.

Toy's statements: According to the majority, the exclusionary rule, which prohibits evidence seized during an illegal search, applies to verbal statements as well as physical evidence. Toy's statements made during an illegal arrest could not be used against him in court.

Johnny Yee's heroin: The heroin Johnny Yee gave agents could not be used against Toy in court, the majority argued. The heroin was not just "fruit of the poisonous tree." The heroin was inadmissible because agents had uncovered it through an "exploitation" of illegality.

However, the heroin could be used against Wong Sun in court. The majority reasoned that it was not uncovered through any exploitation of Wong Sun or an intrusion on his right to privacy.

Wong Sun's statement: Wong Sun's statement was completely unrelated to his illegal arrest, according to the majority. It could be used in court.

Toy's unsigned statement: The majority ruled that Toy's unsigned statement could not be corroborated by Wong Sun's statement, or any other piece of evidence. The Court could not rely on it alone for a conviction.

The majority offered Wong Sun a new trial in light of the findings.

Dissenting Opinion

Justice Tom C. Clark filed a dissent, joined by Justices John Marshall Harlan, Potter Stewart, and Byron White. Justice Clark argued that the court had created "unrealistic, enlarged standards" for police officers who have to make "split-second" decisions about whether to arrest someone. Justice Clark specifically noted that Toy's decision to flee from officers should be considered probable cause. He believed that the arrests were legal and evidence should not be excluded on the basis that it was "fruit of the poisonous tree."


Wong Sun v. United States developed the "fruit of the poisonous tree" doctrine, ruling that even evidence distantly related to an exploitative and illegal arrest should not be used in court. Wong Sun v. United States also extended the exclusionary rule to verbal statements. While it was a landmark case, Wong Sun v. United States did not have the final word on the exclusionary rule. More recent cases have limited the reach of the rule.


  • Wong Sun v. United States, 371 U.S. 471 (1963)
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Spitzer, Elianna. "Wong Sun v. United States: Supreme Court Case, Arguments, Impact." ThoughtCo, Aug. 28, 2020, thoughtco.com/wong-sun-v-united-states-4587791. Spitzer, Elianna. (2020, August 28). Wong Sun v. United States: Supreme Court Case, Arguments, Impact. Retrieved from https://www.thoughtco.com/wong-sun-v-united-states-4587791 Spitzer, Elianna. "Wong Sun v. United States: Supreme Court Case, Arguments, Impact." ThoughtCo. https://www.thoughtco.com/wong-sun-v-united-states-4587791 (accessed May 27, 2022).