Case Western Reserve Law Review
The state plays different roles, and free speech doctrine should (and sometimes does) respect these roles. We properly insist (with some categorical exceptions) that the state not regulate private speech based on subject matter or point of view. If private speakers want to praise the Nazis or condemn homosexuality, the state has no place stopping them, even if firmly convinced these ideas are wrong. Why we have such firm protection for speech we abhor is a matter of much debate. To some extent, it's because we don't trust the state to make content-based judgments consistently as a matter of principle; we fear that too often it will be merely playing favorites, helping friends and harming enemies. One thing we know is that the state holds a monopoly over legitimate coercive force, and that when it jails or fines, it possesses the ability to squelch speech, and not merely channel it to another outlet. We have similarly strict rules against the state's drawing content- based lines in public places where people have traditionally gathered. We may build streets primarily for ease of movement and parks primarily for recreation, but citizens also use both to meet and discuss matters of the day, to face ideas with which they may not be familiar (and sometimes find quite odd). We can always walk by or away from such speech, so we are never captive in these settings. Even if streets and parks are technically "owned" by the state and not by private capital, they are held as a kind of public trust. (That the state is really "we the people" acting via delegation can't get us very far; exploding the public/private line in this sense would raise difficulties in any area of free speech law, regarding whether the state is acting in a sovereign/regulatory or some other capacity.) We have made a collective decision-perhaps in part to ensure that not only the wealthy have adequate avenues for their ideas-to reserve some property as space where the state may not regulate speech based on content.
Abner S. Greene,
Speech Platforms Law Review Symposium 2010: Government Speech: The Government's Ability to Compel and Restrict Speech, 61 Case W. Res. L. Rev. 1253 (2010-2011)
Available at: http://ir.lawnet.fordham.edu/faculty_scholarship/325