Legal Definitions - fruit of the poisonous tree

The legal doctrine of fruit of the poisonous tree is a principle used in criminal law that prevents evidence from being used in a court of law if it was discovered as a direct result of an earlier illegal act by law enforcement. It is an extension of the exclusionary rule, which prohibits the use of evidence obtained in violation of a defendant's constitutional rights.

The metaphor suggests that if the initial evidence (the "tree") is obtained unlawfully—for instance, through an illegal search or interrogation—then any subsequent evidence discovered because of that initial illegality (the "fruit") is also considered tainted and generally inadmissible in court. The purpose of this doctrine is to deter police misconduct by ensuring that law enforcement cannot benefit from breaking the law to gather evidence.

However, there are important exceptions where evidence derived from an illegal act might still be admissible:

• Independent Source: If the evidence was discovered through a separate, lawful investigation that was entirely independent of the illegal activity.
• Inevitable Discovery: If law enforcement can prove that the evidence would have been lawfully discovered anyway, even without the illegal action.
• Good Faith: In some circumstances, if officers genuinely believed they were acting lawfully and the initial illegal act was a technical error, the derived evidence might still be admitted.

Here are some examples illustrating the "fruit of the poisonous tree" doctrine:

• Example 1: Illegal Search Leading to Physical Evidence
  Police officers illegally enter a suspect's apartment without a warrant and find a handwritten note detailing the location of a hidden stash of counterfeit money in a storage locker. Based solely on this note, they obtain a search warrant for the locker and find the money.

  Explanation: The illegal entry into the apartment is the "poisonous tree." The handwritten note found during that illegal entry is the immediate "fruit." The counterfeit money, discovered only because of the information in the illegally obtained note, is also considered "fruit of the poisonous tree" and would likely be inadmissible in court, even though a warrant was later obtained for the locker.

• Example 2: Unlawful Interrogation Leading to a Confession and Witness Testimony
  Detectives interrogate a suspect for several hours without informing them of their right to remain silent or their right to an attorney (Miranda rights). During this unlawful interrogation, the suspect confesses to a robbery and identifies an accomplice. The police then use this information to locate and question the accomplice, who also provides a confession.

  Explanation: The unlawful interrogation (failure to provide Miranda warnings) is the "poisonous tree." The suspect's confession is the immediate "fruit." The accomplice's identity and subsequent confession, obtained directly as a result of the illegally coerced confession, are also considered "fruit of the poisonous tree" and would likely be excluded from evidence against the original suspect.

• Example 3: Illegal Wiretap Leading to Financial Records
  A federal agent illegally places a wiretap on a suspect's phone without obtaining a court order. Through the wiretap, the agent overhears conversations about a specific offshore bank account used for money laundering. The agent then uses this information to subpoena the bank records for that account.

  Explanation: The illegal wiretap is the "poisonous tree." The information about the offshore bank account obtained from the wiretap is the immediate "fruit." The bank records, which were discovered solely by exploiting the illegally obtained information, are also "fruit of the poisonous tree" and would likely be suppressed, meaning they could not be used as evidence in a trial.