Arthur Garfield Hays (December 12, 1881 – December 14, 1954) was an American lawyer and champion of civil liberties issues, best known as a co-founder and general counsel of the American Civil Liberties Union and for participating in notable cases including the Sacco and Vanzetti trial.
He was a member of the Committee of 48 and a contributor to The New Republic.
In 1937, he headed an independent investigation of an incident in which 18 people were killed and more than 200 wounded in Ponce, Puerto Rico, when police fired at them; his commission concluded the police had behaved as a mob and committed a massacre.