The First Amendment, like the constitution generally, only applies to the government. So if the government stops someone from talking, or punishes them, that’s a First Amendment issue. If a private person says 'I won’t hire you or let you be on TV anymore,' that’s not. The idea is we don’t let the government decide what’s a good opinion, but we do let individuals decide what they think is offensive and what should be rewarded and what should be discouraged. That’s the way the marketplace of ideas is supposed to work.
Kermit Roosevelt, ABC News, Dec 20, 2013