Freedom of speech is about law. The first ammendment says:
"Congress shall make no law ... abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."
It doesn't have to, because the effect of any law is to define what you can and cannot do in society without being punished, killed or excommunicated by the society, as represented by the government.
"Congress shall make no law ... abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."