In legal terminology, the phrase “fruit of the poisonous tree” refers to evidence obtained by means of an illegal search or seizure. Under the fruit of the poisonous tree doctrine, if evidence was improperly obtained, it must be excluded from trial to protect against violations of an individual’s constitutional rights (as protected by the Fourth and Fifth Amendments). Courts have also extended this doctrine to make evidence inadmissible if it was derived from evidence that was illegally obtained.
The first application of the concept of this rule was in the 1920 case of Silverthorne Lumber Co. v United States, but the actual phrase “fruit of the poisonous tree” wasn’t used until 1939 by Justice Frankfurter in his ruling on Nardone v. United States.
What makes up the fruit of the poisonous tree doctrine?
The exclusionary rule states that evidence cannot be brought into court if it was in any way obtained in violation of the Constitution. This is why, when a person is under arrest, being questioned or otherwise detained by law enforcement, they must be read their Miranda rights, first established in Miranda v. Arizona — that is, they must be informed of their constitutional rights. If the individual is not informed of their rights, it could be argued that any confessions or information obtained is unconstitutional.
Similarly, the fruit of the poisonous tree doctrine extends the exclusionary rule to evidence that was illegally obtained and makes it inadmissible in court. This metaphor drawn from nature explains how if a source has problems with authenticity, it also leads to problems with the conclusions drawn from it.
Exceptions to the fruit of the poisonous tree doctrine
Three important exceptions apply to the exclusionary rule and this doctrine. Evidence will not be excluded if any of the following apply:
- The evidence was uncovered independently of the illegal activity
- If its discovery was inevitable
- If the evidence was uncovered before the illegal activity
Fruit of the poisonous tree can be used as a defense when someone presents an argument claiming that they were unlawfully arrested or detained. It can also be used to exclude evidence that was obtained from an illegal search. For example, if a detective went into a person’s home without a warrant to gather evidence to use against them in court, the evidence would be considered inadmissible. The fruit of the poisonous tree doctrine ensures that people are not convicted of crimes they did not commit due to improperly collected or obtained evidence.