Wong Sun v. United States

The ruling established the "fruits of the poisonous tree" doctrine. In conformance with the Due Process Clause, the doctrine directs that any evidence resulting from illegal search and seizure, no matter how remotely connected can not be introduced in court. After a court finding of illegality, the government is charged with the responsibility to show that any evidence introduced did not result from knowledge of the illegal evidence. The decision significantly expanded the exclusionary rule which excludes the use of certain evidence in trials. Later Court decisions weakened the rule by creating more exceptions where evidence could be appropriately used. This decision, and others by the Warren Court protecting defendants' rights, led to creation of the public defender system in the United States.

The Fourth Amendment is perhaps one of the most important provisions protecting human liberty in the Constitution. The amendment prohibits "unreasonable" search and seizure by requiring police to obtain a search warrant only after showing "probable cause" to an impartial neutral magistrate. The warrants must describe the particular place to be searched and items to be seized as evidence. Probable cause requires the government to demonstrate that the evidence would lead a person of reasonable caution to the belief that a felony was committed. The Court in the 1948 Johnson v. United States case reaffirmed the role of "a neutral and detached magistrate" to assess probable cause and issue warrants rather than relying solely on the instantaneous judgement of "zealous officers . . . engaged in the often competitive enterprise of ferreting out crime." Because the Fourth Amendment did not provide remedies for violations, the Court in the 1914 Weeks v. United States case created the exclusionary rule to deter police misconduct. The rule excluded from trials evidence gained through illegal searches and seizures.

Early on a June morning in 1959, after six weeks of surveillance, federal narcotics agents in San Francisco arrested Hom Way for heroin possession. Upon arrest, Way stated he had purchased heroin from a person known as "Blackie Toy," owner of a laundry elsewhere in town. The police proceeded promptly to a laundry in the vicinity indicated by Way. When a street-clothed agent announced at the door of the closed laundry that he was a narcotics agent, James Wah Toy slammed the door and fled to a rear residence room with his family. The agents broke through the door and pursued Toy through the laundry and residence. A search uncovered no narcotics. Upon arrest, Toy denied selling narcotics but indicated another person named "Johnny" did and described where "Johnny" could be found. The agents then proceeded promptly to the residence described, which they entered, and where they discovered Johnny Yee in a bedroom. A search revealed less than an ounce of heroin. Upon his arrest Yee stated the heroin was obtained from Toy and another person named "Sea Dog" who Toy identified as Wong Sun. The agents next proceeded to Sun's residence which they entered and where they found Sun still sleeping. A search uncovered no narcotics. Toy, Yee, and Sun were arraigned on violation of federal narcotics laws and released. Several days later they returned for interrogation. No attorneys were present during the questioning. An agent prepared written statements based on comments made by the three and each reviewed them for accuracy. They, however, refused to sign the statements though admitting to their accuracy.

At the resulting trial without a jury in the U.S. District Court for the Northern District of California, Way did not testify and Yee, the principal witness, repudiated his own unsigned statement. The court excused Yee to avoid self-incrimination. Four items of evidence were therefore introduced to support the government's case: (1) statements by Toy in his bedroom while being arrested; (2) heroin taken from Yee; (3) Toy's unsigned pretrial statement; and (4) Sun's pretrial statement. The defense objected to the use of these "fruits" of their alleged unlawful arrests and searches. Yee and Sun were found not guilty of conspiracy charges, but convicted "of fraudulent and knowing transportation and concealment of illegally imported heroin."

An appeal to the Court of Appeals for the Ninth Circuit resulted in affirmation of the conviction. Though the appeals court held that the arrests violated the Fourth Amendment's requirement of warrants based on "probable cause" and "reasonable grounds," the court ruled the four items of evidence "were not the fruits of the illegal arrests," and, therefore, were properly admitted as evidence. The court found neither Way nor Yee to be proven reliable informants to justify the arrests of Toy and Sun without warrants. The Supreme Court then granted certiorari to hear the case. The Court's interest in the case focused on the trial judge's acceptance of the four items of evidence.