10. Mapp v. Ohio began the process of solidifying the rights of defendants by dictating illegally obtained evidence should be regarded as inadmissible at trial
Receiving an anonymous tip concerning the operations of an illegal gambling racket, police officers in Cleveland, Ohio, attempted to search the house of Dollree Mapp on May 23, 1957. Refused entry without a warrant, a host of officers returned thirteen hours later and forced entry. Presenting a piece of paper claimed to be a warrant, taken from Mapp’s possession following her arrest and never seen again, the police conducted a search of the property. Charged with various crimes, Mapp was eventually sentenced to one year in prison after refusing to testify against her alleged collaborators.
Appealing to the Supreme Court on the grounds the police had no probable cause to suspect her personal involvement, Mapp’s lawyers approached the case from the perspective of the Fourth Amendment. Contending seized books could not be used as evidence at trial of illegal gambling, for they were obtained without a warrant and thus illegally recovered, the Supreme Court sided with Mapp by 6-3. Overturning her conviction, the court issued a widespread proclamation ruling that articles seized unlawfully by any authorities, state or federal, must be excluded from evidence at trial as opposed to the previous interpretation of only affecting federal legal scenarios.