The first 5 words of the 1st Amendment to the US Constitution are "Congress shall make no Law". So all the rights mentioned in the 1st Amendment (free speech, freedom of religion, etc) are protected from infringement
by the federal government, and only the federal government.
People like to assume the rights in the 1st Amendment are blanket privileges. But they are not, hence the laws against libel and slander, inciting riots, hate speech, etc.
So if someone tells you to STFU because they don't want to hear what you're saying, they're not violating any of your rights. In contrast, they are practicing THEIR right to free speech, by telling you what they think of you. It's a two-way street.
[This message has been edited by Blacktree (edited 04-19-2014).]