Final answer:
In Mapp v. Ohio, the Supreme Court ruled that evidence obtained through illegal searches and seizures cannot be used in a trial to uphold the Fourth Amendment, leading to the exclusionary rule and the principle of the 'fruit of the poisonous tree.'
Step-by-step explanation:
Mapp v. Ohio Case and the Exclusionary Rule
According to the Supreme Court's decision in the Mapp v. Ohio case, evidence that is illegally seized cannot be used in a trial because it violates the Fourth Amendment, which protects against unreasonable searches and seizures. The case established the exclusionary rule at a federal level, which was first applied in Weeks v. United States in 1914. The Court, in a historic decision, stated that all evidence obtained by searches and seizures in violation of the Constitution is inadmissible in a state court. This includes not just the directly seized evidence but also any additional evidence that is uncovered as a consequence of the illegal act—following the principle of the 'fruit of the poisonous tree.'
The exclusionary rule is intended to deter law enforcement from conducting illegal searches and to maintain the integrity of the judicial process. However, there are exceptions to the rule such as the 'good faith' exception and the 'inevitable discovery' rule.