If a police officer questions a suspect without giving the suspect the Miranda warning, nothing the suspect says can be offered into evidence against the suspect at trial. Moreover, under the "fruit of the poisonous tree" rule, any evidence which the police find as the result of a lead obtained during questioning which violates the Miranda rule is equally inadmissible at trial.
Case Example 1: Mal Addy is arrested for assault with a deadly weapon. Without advising Addy of his Miranda rights, the police ask Addy about the location of the knife that Addy allegedly used in the attack. Addy tells the police of its hidden location. The absence of the Miranda warning makes what Addy said to the police inadmissible at trial.
Question: Can the prosecutor introduce the knife into evidence against Addy?
Answer: No. The knife is the "fruit of a poisonous tree." The police learned of the knife solely through an improper interrogation of Addy, so the knife is inadmissible as evidence. If the police would have inevitably discovered the evidence that they initially discover because of an illegal questioning, however, the evidence may be admitted against the suspect despite the "poisonous fruit" doctrine.
Case Example 2: Assume the same facts as above, except that Addy tells the police that the knife is in the backpack Addy had on at the time of his arrest. The police would have found the knife when they inventoried the contents of the backpack during the booking process.
Question: Is the knife admissible in evidence against Addy at trial?
Answer: Yes. Since the police would inevitably have found the knife even if Addy had said nothing, the knife is not the fruit of the improper questioning.
Moreover, under the "fruit of the poisonous tree" rule, any evidence which the police find as the result of a lead obtained during questioning which violates the Miranda rule is equally inadmissible at trial. 加之，依据毒树之果的原则，警察因违反米兰达规则获得线索而得到的证据，同样在审判是不能采用。