Which case established the principle that evidence obtained illegally cannot be used in court?

The case that established the principle that evidence obtained illegally cannot be used in court is Mapp v. Ohio. This 1961 Supreme Court decision ruled that the exclusionary rule, which prevents the use of illegally seized evidence in both federal and state courts, applies to state law enforcement through the Fourteenth Amendment. The case arose when police officers conducted a search of Dollree Mapp's home without a proper warrant and found illegal items. Mapp challenged the admissibility of this evidence in court, leading to the ruling that not only federal but also state courts must adhere to the exclusionary rule. This decision reinforced the protection of citizens' Fourth Amendment rights against unreasonable searches and seizures, establishing a crucial precedent in American legal proceedings.

Other cases listed, such as Texas v. Johnson, Miranda v. Arizona, and Roe v. Wade, involve significant legal principles regarding free speech, the rights of the accused during police interrogations, and reproductive rights, respectively, but none directly address the issue of the admissibility of illegally obtained evidence in court.