In 1943, the Supreme Court handed down West Virginia State Board of Education v. Barnette. With Justice Robert H. Jackson writing for the six-Justice majority, the Court upheld the First Amendment right of Jehovah's Witnesses schoolchildren to refuse to salute the flag or recite the Pledge of Allegiance, state-imposed obligations that the children and their parents contended were acts of idolatry that violated biblical commands. Judge Richard A. Posner has said that Justice Jackson's effort "may be the most eloquent majority opinion in the history of the Supreme Court."
Douglas E. Abrams,
Justice Jackson and the Second Flag-Salute Case: Reason and Passion in Opinion-Writing, 36 Journal of Supreme Court History 30
Available at: https://scholarship.law.missouri.edu/facpubs/736