Lau v. Nichols (1974)
This unanimous U.S. Supreme Court decision outlawed policies of educational neglect for English language learners. It requires school districts to "take affirmative steps to overcome language barriers" that obstruct students' access to the curriculum. Lau prompted the federal government to enforce the educational rights of language-minority students throughout the country, and remains the most important legal precedent in this area.

Plyler v. Doe (1982)
This case established the right of the children of undocumented immigrants to attend public schools in the United States. This landmark Supreme Court ruling still stands, although it has been repeatedly challenged by anti-immigrant campaigns and initiatives, such as Proposition 187 in California.

Castaneda v. Pickard (1981)
In this case, the 5th U.S. Circuit Court of Appeals ruled that "good faith" efforts by school districts in serving ELLs is not sufficient. It established a "three-prong test" to ensure that local officials were meeting their obligations: Programs must be based on a sound educational theory, supported by adequate resources including trained personnel, evaluated for effectiveness and restructured if necessary. Castaneda has become a cornerstone of civil-rights enforcement over the past two decades.

Meyer v. Nebraska (1923)
The first language rights case ever decided by the U.S. Supreme Court, Meyer struck down a state law that made it a crime to teach in a foreign language before the 8th grade. It defines choice of language as an important civil liberty.