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What Is the Exclusionary Rule?


The Fourth Amendment to the United States Constitution is written to protect New Yorkers and other Americans from the unreasonable searches and seizures of law enforcement officials. However, when it was initially added to the Constitution the rule did not stop those officers and agents of the government from using illegally collected evidence to secure convictions of the individuals they arrested. In 1914 the United States Supreme Court provided clarity in the law regarding this deficiency.

In the case of Weeks v. United States, the high court mandated that evidence seized by a federal agent without cause could not be used against the accused. The Supreme Court later extended what became known as the exclusionary rule to the states in the case of Mapps v. Ohio.

The exclusionary rule has been further broadened by the “fruits of the poisonous tree” doctrine. Under this legal concept, not only may a court exclude illegally obtained evidence against a defendant but also any evidence that was obtained consequent to the excluded illegal material. Under these rules criminal defendants in the United States have greater protections under the Fourth Amendment than they had as it was originally written.

The Fourth Amendment, the exclusionary rule and the fruits of the poisonous tree doctrine are all intended to protect citizens from misconduct by law enforcement officials. However, these rules and laws are not always correctly applied and mistakes are often made in the preparation of evidence for criminal cases. To challenge evidence and its legal bases for inclusion in a case, a criminal defendant may wish to enlist the help of a legal professional who practices criminal law.