How did Mapp v. Ohio affect US citizens?

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pohnpei397 | College Teacher | (Level 3) Distinguished Educator

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The Supreme Court case of Mapp v. Ohio (decided in 1961) affected US citizens (and everyone who lives in the United States) by saying that state law enforcement officers could not use evidence obtained through illegal searches and seizures in court.  In technical terms, it applied the exclusionary rule to the states.

The 4th Amendment says that government officials cannot conduct searches or seizures without warrants.  However, the amendment does not spell out what happens if they do conduct such searches.  The exclusionary rule (made up by the Supreme Court) says that the evidence found in such searches cannot be used against a defendant in court.  This is the punishment for violating the 4th Amendment—you do not get to use the evidence you have found.

However, the 4th Amendment only applied to the national government.  Most police forces are controlled by the various states (local police forces are included in this).  This meant that state and local police were not subject to the exclusionary rule.  This changed with Mapp.  This case applied the exclusionary rule to the states.  It affected US citizens by protecting them from having evidence used against them in court if that evidence was gained through an illegal search or seizure.


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