The 1943 case was about public school students, and the original defendants were Jehovah’s Witnesses.
However the Court wrote a much broader opinion based on the free speech clause rather than the free exercise of religion clause.
To underscore its intent, the court announced its decision on Flag Day.
Writing for the 6-3 majority, Justice Jackson concluded with:
“If there is any fixed star in our constitutional constellation, it is that no official, high or petty, can prescribe what shall be orthodox in politics, nationalism, religion, or other matters of opinion or force citizens to confess by word or act their faith therein.”