Mapp v. Ohio

U.S. Case Law

Legal Definition of Mapp v. Ohio 

367 U.S. 643 (1961), established that illegally obtained evidence cannot be produced at trial in a state court to substantiate criminal charges against the defendant. The Court relied on the earlier decision in Weeks v. United States, 222 U.S. 383 (1914). Weeks established the exclusionary rule, which states that a person whose Fourth Amendment protections against unreasonable search and seizure have been violated has a right to exclude any evidence so obtained from use in a court of law. In Mapp the Court held that the exclusionary rule had to be applied universally to all criminal proceedings, overturning the ruling in Wolf v. Colorado, 338 U.S. 25 (1949), insofar as it failed to hold the exclusionary rule applicable to state court proceedings, and thus greatly broadening the constitutional protections available to defendants. In United States v. Leon, 468 U.S. 897 (1984), the court validated an exception to the exclusionary rule, holding that evidence which is obtained “in good faith” with a search warrant that is later ruled invalid remains admissible, a central point made in support of the decision being the unacceptable social cost of excluding such evidence.

Learn More about Mapp v. Ohio

Share Mapp v. Ohio

Comments on Mapp v. Ohio

What made you want to look up Mapp v. Ohio? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

evasion of direct action or statement

Get Word of the Day daily email!

Test Your Vocabulary

Great Scrabble Words—A Quiz

  • scrabble-tiles-that-read-scrabble-quiz
  • Which of the following Q-without-U words means the number five in cards or dice?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!