Final answer:
The exclusionary rule prevents evidence obtained through illegal searches or seizures without a warrant from being used in court. This includes both the evidence found during the illegal act and any evidence discovered as a result (fruit of the poisonous tree), although there are certain exceptions.
Step-by-step explanation:
In the event of an illegal search or seizure without a warrant, any evidence of a crime found cannot be used in court due to the exclusionary rule. This rule is a fundamental legal principle in the United States that was developed to protect constitutional rights and ensure that law enforcement officials adhere to legal standards. The landmark cases that established this rule are Weeks v. United States (1914) and Mapp v. Ohio (1961). In Mapp, the Supreme Court held that evidence obtained via searches and seizures in violation of the Fourth Amendment is inadmissible in a state court. The exclusionary rule also extends to what is known as the 'fruit of the poisonous tree.' This means that not only is the directly obtained evidence inadmissible, but also any other evidence that was subsequently discovered as a result of the initial illegal search. However, there are exceptions to the rule, such as the 'good faith' exception or the 'inevitable discovery' exception, where evidence could still be admissible.