Fruit of the Poisonous Tree

Fundamentals of Procedural Law by Adam J. McKee

The concept of the “Fruit of the Poisonous Tree” is a fascinating part of our legal system. This concept extends from the Exclusionary Rule, which we’ve discussed before. The Exclusionary Rule tells us that evidence gathered in violation of a defendant’s constitutional rights can’t be used against them in court. The Fruit of the Poisonous Tree doctrine goes a step further—it says that any evidence derived from illegally obtained evidence is also tainted, or “poisoned,” and generally can’t be used in court.

The Origin of the Doctrine

This colorful term was first used in the case of Nardone v. United States in 1939. The Supreme Court, in its decision, likened illegally obtained evidence to a “poisonous tree.” Any evidence derived from this “tree” would be considered “fruit” that has also been “poisoned.”

Exceptions to the Rule

However, like most rules in law, the Fruit of the Poisonous Tree doctrine also has its exceptions. There are instances where the courts will permit the use of this “fruit,” or derived evidence. This typically happens in three scenarios:

Independent Source Doctrine

The Independent Source Doctrine is a notable exception to the Fruit of the Poisonous Tree doctrine and plays a crucial role in some legal proceedings. This rule applies when the evidence in question was obtained from an entirely separate source that was not connected to the initial, tainted evidence. The concept is that if the information was found independently and without any relation to the original illegally obtained evidence, it retains its untainted status and thus can be admissible in court. One landmark case that illustrates this doctrine is Segura v. United States (1984).

In this case, police officers illegally entered a residence and briefly observed drug evidence. The residents were arrested, and the apartment was secured from the outside to preserve evidence while the officers obtained a search warrant. The Supreme Court ruled that the evidence seized under the warrant was admissible because the warrant was based on information known to the police before the illegal entry, making it an independent source of the evidence. This case shows how the Independent Source Doctrine can be used to ensure that evidence that would have been discovered legally is not discarded due to an unrelated violation.

Inevitable Discovery Doctrine

The Inevitable Discovery Doctrine is another critical exception to the Fruit of the Poisonous Tree rule. This principle posits that if the evidence in question would have inevitably been uncovered, even without the tainted evidence, through lawful means, it can still be deemed admissible. The basis of this doctrine is the premise that exclusion of the evidence is not necessary as a deterrent because the police would have discovered it even without the illegal action. A prominent case that brought this doctrine to the fore is Nix v. Williams (1984).

In this case, a murder suspect had been improperly interrogated without his attorney present, leading him to reveal the location of the victim’s body. The Supreme Court ruled that, although this was a violation of the defendant’s Sixth Amendment right, the physical evidence could be admitted at trial because a search party was already on route to the body’s location and would have discovered it imminently. This case underscored the use of the Inevitable Discovery Doctrine, demonstrating how evidence that would inevitably have been found through legal means can be permitted in court despite an unrelated constitutional violation.

Attenuation Doctrine

The Attenuation Doctrine is yet another important exception to the Fruit of the Poisonous Tree rule. This principle applies when the connection between the illegal action and the subsequent discovery of evidence is so attenuated, or weakened, that the taint from the initial illegality is no longer present. The evidence is admissible if the linkage between the unlawful conduct and the discovery of the evidence is sufficiently distant or has been interrupted by some intervening circumstance. The case of Wong Sun v. United States (1963) significantly featured the Attenuation Doctrine.

In this case, Wong Sun had been illegally arrested, and a verbal statement he made led to the discovery of drugs. However, Wong Sun was released and then voluntarily returned to the police station a few days later, where he made incriminating statements. The Supreme Court held that the later statements were admissible because the connection between the illegal arrest and the later statements had become so attenuated due to the passage of time and Wong Sun’s voluntary act to return to the police. This case showcases how the Attenuation Doctrine can lead to the admissibility of evidence initially tied to an illegal action but subsequently distanced from that taint.

Landmark Cases Review

Silverthorne Lumber Co. v. United States (1920)

This case helped establish the Fruit of the Poisonous Tree doctrine. Here, federal officers conducted an unlawful search of the Silverthorne Lumber Co.’s premises and made copies of various business papers. The Court held that the copies were inadmissible, asserting that the government could not use illegally obtained evidence as a basis for gaining additional, admissible evidence.

Wong Sun v. United States (1963)

The Court in Wong Sun v. United States applied the doctrine explicitly. It found that verbal evidence, as well as physical evidence, could be the “fruit” of illegal police action and thus could be excluded.

Nix v. Williams (1984)

The Court, in this case, established the Inevitable Discovery exception. It found that illegally obtained evidence can be admitted if it can be shown that the evidence would have been found eventually by lawful means.


The Fruit of the Poisonous Tree doctrine is a significant extension of the Exclusionary Rule, preventing not just illegally obtained evidence but also any evidence derived from it from being used in court. Despite some exceptions, its application underscores the importance of upholding constitutional rights in the criminal justice system.



Modification History

File Created:  08/08/2018

Last Modified:  07/24/2023

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