When a protest crosses the line from speech to action, the government can intervene more aggressively. Political protesters have the right to picket, to distribute literature, to chant and to engage passersby in debate. But they do not have the right to block building entrances or to physically harass people. The ACLU has often been at the center of controversy for defending the free speech rights of groups that spew hate, such as the Ku Klux Klan and the Nazis. But if only popular ideas were protected, we wouldn't need a First Amendment.
History teaches that the first target of government repression is never the last.
If we do not come to the defense of the free speech rights of the most unpopular among us, even if their views are antithetical to the very freedom the First Amendment stands for, then no one's liberty will be secure. We should not give the government the power to decide which opinions are hateful, for history has taught us that government is more apt to use this power to prosecute minorities than to protect them. At the same time, freedom of speech does not prevent punishing conduct that intimidates, harasses, or threatens another person, even if words are used. Threatening phone calls, for example, are not constitutionally protected. The Supreme Court has recognized the government's interest in keeping some information secret, such as wartime troop deployments.