Meyer v. Nebraska
Meyer v. Nebraska was a 1923 decision of the U.S. Supreme Court overturning, by a vote of 7-2, a Nebraska state law which prohibited the teaching in schools, whether private or public, of modern languages other than English to any child who had not graduated from the eighth grade.
The Court based its decision on the Due Process Clause of the Fourteenth Amendment (which states, in part, ". . . nor shall any State deprive any person of life, liberty, or property, without due process of law . . ."), holding that the liberties so protected by that Clause include the right of an individual "to contract, to engage in . . . common occupations, to acquire useful knowledge", etc.
The decision became an important milestone in the development of the doctrine of substantive due process and later served as a precedent for a constitutional right of privacy.