Illegally Obtained Evidence
Because a police officer or any law enforcement agent is prohibited from conducting illegal searches and seizures, any evidence obtained as a result of an illegal search or seizure is considered illegally obtained. The illegal act has "tainted" the evidence and it will be excluded from trial. This "exclusionary rule" is also known as the "fruit of the poisonous tree" doctrine, a standard that has long been applied to police investigations. The "fruit" is not only the evidence first obtained, but also any other evidence or testimony the police obtain thereafter as a result of the illegal search or seizure. The purpose of the exclusionary rule is to deter police misconduct in search and seizure situations.
Before the trial begins, the defense will make a "motion to suppress" the evidence in question, arguing that it must be excluded because law enforcement officials obtained it through an illegal procedure. The prosecutor will argue that either the evidence was not illegally obtained, or that an exception exists, allowing the evidence in. The judge then decides whether or not the evidence will be admitted for the jury to consider. If the motion is granted, the evidence is ruled inadmissible and excluded from trial. Evidence that may be excluded typically includes confessions obtained and statements made during an interrogation where Miranda warnings were not given, or items that were recovered during an illegal search.
Good Faith Exception
Evidence that the police find in an illegal search is sometimes admitted under the "good faith exception" to the exclusionary rule. If an adult in your home allows the police to search the premises in your absence, a judge could find that the officers had a good faith belief that the adult had some authority to consent. For example, a police officer could reasonably believe that a college student who is back at home for a visit can give consent to search her parent's home. The officer's belief that he was authorized to enter, although mistaken, means the evidence he finds will be admitted under the good faith exception. One of the most common examples of the good faith exception is where police rely on a defective search warrant or believe that the warrant has been issued when it has not.