The issue in this case was whether compulsory flag salutes in public schools were constitutional. The Court held that they were not. This is one of my favorite Scotus passages because it emphasizes the perennially important point that difference is to be protected:
"But freedom to differ is not limited to things that do not matter much. That would be a mere shadow of freedom. The test of its substance is the right to differ as to things that touch the heart of the existing order. 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."
from the Supreme Court in West Virginia State Board of Education v. Barnette