American Civil Liberties Union (ACLU)

The American Civil Liberties Union, or ACLU, is the nation’s largest and oldest civil liberties organization. Its mission is to defend and preserve the rights and liberties of people in the United States. In the nearly 100 years since its founding, the American Civil Liberties Union has played a key role in many of the nation’s most important constitutional cases and appeared before the United States Supreme Court more than any other private organization.