The American Civil Liberties Union (ACLU) is an American nonprofit organization founded in 1920 "to defend and preserve the individual rights and liberties guaranteed to every person in this country by the Constitution and laws of the United States". The ACLU works through litigation and lobbying and has over 1,800,000 members as of July 2018, with an annual budget of over $300 million. Affiliates of the ACLU are active in all 50 states, Washington, D.C., and Puerto Rico. The ACLU provides legal assistance in cases where it considers civil liberties at risk.
Legal support from the ACLU can take the form of direct legal representation or preparation of amicus curiae briefs expressing legal arguments when another law firm is already providing representation.