One of the glories of the Western Enlightenment, especially as embodied in the lifeblood of political democracies, is freedom of expression.
This freedom gives people the right to voice their opinions in public spaces, airing unpopular, tasteless, and provocative ideas – and especially those critical of the prevailing political order.
In the United States, particularly, ideas are extended to symbolic acts such as burning the flag as a way of repudiating official policies, or more broadly, the compulsions of nationalism and patriotism.
The US Supreme Court has generally taken a very broad view of freedom of expression, but it finds some outer limits.
It indicated famously that it would validate laws prohibiting members of a movie audience from falsely shouting “fire!” in a crowded theatre, as it explained that the likely result is panic and a stampede that can hurt or kill.
Even at the height of the Cold War, with McCarthyism creating waves of conformity, the endorsement of Communist ideas were generally allowed, although loyalty oaths for certain types of employment were imposed and actual.