The fruit of the poisonous tree doctrine prohibits the admission of evidence that stems from that which was obtained in an illegality in a criminal case. The doctrine was established to deter law enforcement from misconduct and illegal searches and seizures.
What is the “Fruit of the Poisonous Tree” Doctrine?
The “fruit of the poisonous tree” doctrine extends the exclusionary rule which excludes all illegally obtained evidence from getting admitted in a criminal trial. The “fruit of the poisonous tree” refers to all evidence that stems from original evidence that was illegally obtained. The original illegal evidence is considered to be the poisonous tree, and any evidence that stems from this tree is considered to be tainted by the poison.
The purpose of the fruit of the poisonous tree doctrine is to deter police misconduct and prohibit illegal searches and seizures to acquire evidence. For example, if the police coerce a confession from a suspect, obtain a search warrant from the coerced confession, or conduct an illegal interrogation that produces the discovery of physical evidence, the doctrine prohibits the confession and the physical evidence from becoming admitted in criminal proceedings. In most criminal cases, the doctrine is applied when a criminal defense attorney files a motion to exclude evidence that would adversely affect a defendant’s case.
The fruit of the poisonous tree doctrine applies to all personal testimony in a criminal case, as well as all physical evidence obtained by illegal means, with the following exceptions:
Although the doctrine was established to deter police misconduct that is deliberate, reckless, or grossly negligent, it may not prevent all types of evidence from getting admitted in a criminal case if it only causes marginal deterrence.
The court assesses whether the evidence in question was discovered by illegal means by independent legal sources. Evidence that is acquired through independent legal sources is not prohibited by the fruit of the poisonous tree doctrine. Even if evidence was originally discovered by an unlawful search and seizure, the evidence can still be admitted in some cases.
The independent source doctrine does not affect future evidence discovered in a case. For example, courts do not connect future evidence that’s independently acquired to prior evidence that’s tainted.
The doctrine does not apply to inevitable discovery. If it’s inevitable that evidence would have been eventually discovered by law enforcement without an illegal search, the evidence is admissible in court.