Justice William J. Brennan, Jr.,Brennan, William J., Jr.;Keyishian v. Board of Regents[Keyishian v. Board of Regents] wrote the decision for the 5-4 majority that struck down a New York law requiring public school teachers to swear a loyalty oath certifying that they were not communists or members of allegedly subversive organizations. The Supreme Court ruled that the law deprived them of their free speech rights and meant a citizen had improperly to risk losing constitutional rights in order to accept public employment. A major part of the law’s failing was its unconstitutional vagueness that did not separate advocacy of an abstract doctrine from actual incitement to violence. Justices Tom C. Clark, John M. Harlan II, Potter Stewart, and Byron R. White dissented.Loyalty oaths;Keyishian v. Board of Regents[Keyishian v. Board of Regents]

Academic freedom

Aptheker v. Secretary of State

Bad tendency test

Clear and present danger test

Cold War

Communist Party v. Subversive Activities Control Board

Dennis v. United States

Scales v. United States

Speech and press, freedom of

Yates v. United States