What are the optimal limits of free speech in a democratic society?

“The traditional debate over free speech often treats words as neutral vessels of information and the speaker as the sole protagonist. To deepen this inquiry, we must look at the hidden mechanics of how words act upon the world, who is systematically silenced before they even speak, and the neglected rights of those who listen.”

“The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others”