Arthur Garfield Hays (December 12, 1881 – December 14, 1954) was an American lawyer who became prominent in civil liberties issues; he was a co-founder of the American Civil Liberties Union and served as general counsel beginning in 1920. He also took private cases and became wealthy representing powerful or controversial clients, participating in notable cases such as 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.
Hays wrote several books and essays about civil liberties issues, and in 1942 published his autobiography, City Lawyer: The Autobiography of a Law Practice.
Hays was born in Rochester, New York. His father and mother, both of German Jewish descent, belonged to prosperous families in the clothing manufacturing industry. After graduating from Columbia College in 1902, where he was one of the early members of the Pi Lambda Phi fraternity, and Columbia Law School in 1905, Hays formed a law firm with two of his former classmates.
Hays and his partners gained prominence during World War I representing interests of ethnic Germans in the United States, who were discriminated against because Germany was an enemy of the Allies during the war.
Hays was active in civil liberties issues and in 1920 was hired as general counsel for the American Civil Liberties Union. From this point, his career had two tracks: he vigorously defended the individual liberty of victims of discriminatory laws, but he also kept private work. He became a wealthy lawyer who represented the interests of power and fame (his more prominent clients ranged from Wall Street brokers and best-selling authors to notorious gamblers and the Dionne quintuplets.)