Keyishian v. Board of Regents, 385 U.S. 589 (1967), was a United States Supreme Court case in which the Court held that states cannot prohibit employees from being members of the Communist Party and that this law was overbroad and too vague.

The regents of the State University of New York also required teachers and employees to sign an oath that they were not members of the Communist Party.

Some faculty and staff of the university were terminated for refusing to sign the oath and appealed to the Supreme Court.

The Supreme Court, in a 5–4 decision,[2] overturned the New York state laws prohibiting membership in seditious groups because it was too vague and was overbroad.

That largely reversed the 1952 decision in Adler v. Board of Education, in which Irving Adler had been dismissed for the New York City public school system because of a previous connection with the Communist Party USA.