The Fourth Amendment to the US Constitution protects you against unreasonable searches and seizures. Generally, this means that the police or other law enforcement agents can't search your property and take your things simply because they don't like you or just because they feel like it. They must have a good reason before they can search your home or office and seize things, such as contraband or evidence of a crime. When the Fourth Amendment is violated, any evidence that can be traced to the illegal search or seizure is fruit of the poisonous tree and can't be used against you.
Excluding or "Suppressing" Evidence
The tool used to enforce the Fourth Amendment's protections is called the "exclusionary rule . Generally, unless one of the warrant exceptions applies, the police and other government agents need a search warrant before they can search your home, office, luggage, or even your pockets. A search that's made without a warrant, or in violation of a warrant, is considered an unreasonable search. And, under the exclusionary rule, any evidence that's obtained in violation of the Fourth Amendment - that is, through an illegal or unreasonable search, seizure or even an arrest - can't be used as evidence against you to convict you of a crime. The evidence is "excluded" or "suppressed."
For example, say police officers get a search warrant that authorizes them to search your backyard for growing marijuana plants. They don't find any plants in your yard. However, during the search, an officer enters your basement and finds bundles of packaged marijuana and seizes them. You're then arrested and charged with possession of illegal drugs. Under the exclusionary rule, unless the prosecution can convince the judge at trial that the officer was justified in entering the basement, the marijuana will be excluded from evidence and can't be used against you because the search and seizure was illegal - the police were authorized to search only your backyard.
Fruit of the Poisonous Tree
The "fruit of the poisonous tree" doctrine goes hand-in-hand with the exclusionary rule. In fact, it takes the protection given by the exclusionary rule one step further. Under this doctrine, the state can't use evidence at trial against you if it was discovered through other evidence that was obtained in violation of the Fourth Amendment. The "poisonous tree" is evidence first seized or discovered through the initial violation of the Fourth Amendment - an illegal search, seizure, or arrest. The "fruit" is any evidence that's uncovered later because of information or evidence obtained from that illegal search, seizure or arrest.
Both the exclusionary rule and the fruit of the poisonous tree doctrine are designed to curb or deter misconduct by police and other government agents. They work on the assumption that the police will do their best to make sure that they don't violate the Fourth Amendment if they know that they can't benefit from any evidence found or uncovered as result of an illegal search or seizure.
Fruit of the Poisonous Tree in Action
Perhaps the best way to understand how the fruit of the poisonous tree doctrine works is to look at some examples. There's really no limit to the scenarios in which the doctrine may apply, but consider:
Example 1: A police officer stops a car for speeding. The driver hasn't been drinking or using any type of drugs, and she's given the officer no reason to believe that she's driving while drunk or impaired. The officer asks for consent to search the trunk of the car, but the driver refuses to let him. The officer then orders her out of the car and he searches the inside of the car and the trunk. He finds marijuana in the trunk, and he arrests the driver for drug possession.
The officer then goes to a magistrate and gets a warrant for the driver's home because he believes she's selling marijuana. The magistrate gives him the warrant because he thinks the officer has enough evidence that the driver is committing a crime and that her house contains evidence of the crime. The officer searches the home and finds more marijuana along with other illegal narcotics and illegal firearms. The driver is then charged with a gun-related crime on top of the drug possession charge.
Under the exclusionary rule, the marijuana found in the car can't be used against the driver because the search of the car was illegal. All the other evidence found in the driver's home can't be used against her because it's fruit of the poisonous tree - it was discovered through evidence found through an illegal search.
Example 2: The police arrest someone who's suspected of committing an armed bank robbery. The police begin questioning or "interrogating" the suspect, and they make him aware of his Miranda rights, including his right to have an attorney present during the questioning. The suspect immediately tells the police that he wants an attorney, but the police continue the interrogation. After a few hours, the suspect confesses to the crime and tells them that the money stolen from the bank is hidden in his home. The police get a warrant, search the home, and along with the money, they find dozens of pieces of stolen goods and a large quantity of cocaine. The suspect is then charged with theft and drug trafficking on top of the armed robbery charge.
Under the exclusionary rule, the suspect's confession to armed robbery can't be used because it was obtained though an illegal interrogation. The money from the bank, as well as the other stolen goods and cocaine found in his home, can't be used against him either because they're all fruits of the illegal interrogation, that is, the poisonous tree.
Questions for Your Attorney
- How exactly do I go about having evidence suppressed if I think it was obtained illegally?
- A judge refused to suppress evidence that my court-appointed attorney argued was fruit of the poisonous tree. I was convicted. Can I appeal the judge's decision not to exclude the evidence? What if I think my attorney made a mistake?
- Once we get the evidence excluded the prosecution will have to drop the case against me, right?