Roger Nash Baldwin (January 21, 1884 – August 26, 1981) was one of the founders of the American Civil Liberties Union (ACLU).

He also co-wrote Juvenile Courts and Probation with Bernard Flexner at this time; this book became very influential in its era, and was, in part, the foundation of Baldwin's national reputation.

After the passage of the Selective Service Act of 1917, Baldwin called for the AUAM to create a legal division to protect the rights of conscientious objectors.

[4] In the meantime, on 30 October 1918, as a conscientious objector himself, refusing even to register for the draft, undergo medical examination, or accept any alternative service such as farming, was sentenced at the Federal Court in New York City to a year in a penitentiary.

A fully accessible archive of his correspondence with I.W.W branches, investigators and attorneys has been published by Princeton's Mudd Manuscript Library.

Later, however, as more and more information came out about Joseph Stalin's regime in the Soviet Union, Baldwin became more and more disillusioned with communism and in 1953 called it "A NEW SLAVERY" (capitalized in the original).