ETHICS AND MOTIVATION: Eugene Volokh points out that when private individuals boycott others or fire them because of their speech there is no First Amendment violation. Private actors cannot violate your First Amendment rights -- only the government can do that. The First Amendment creates no obligation on the part of private citizens to listen to you, support you, purchase your products, or associate with you in any way. Eugene then asks whether or not it is ethical to retaliate economically against people you disagree with. Is it morally acceptable for me to not only refuse to buy your product, but to also try and convince others not to do so either?
As with many ethical issues, the answer comes down to motivation. The same action, taken with differing motives, can be either right or wrong -- let's consider a concrete example. Michael Moore is an annoying blowhard who regularly speaks against my Constitutional right to keep and bear a gun. This makes me angry, especially because he uses his mild celebrity as a platform for advocating his views and is eager to lie to further his cause. If I supported a boycott of Michael Moore's "work" based on my loathing for him personally and a desire to see him die pennyless in the gutter, I do not believe that my motivations would be ethical; my actions would be primarly based on spite and a desire to harm, and I don't think that would be right.
However, I could alternatively be inclined to support such a boycott based on my belief that Moore's positions are harmful both to me personally, and to the country as a whole. I believe that having less restrictive gun laws would save hundreds of lives every year, and by speaking out against such a possibility (and even calling for more restricive laws) Michael Moore is directly involved in promoting these deaths. His ability to advance this agenda is based on his celebrity and fame, and so by supporting a boycott against him and his work I can undercut the source of his power to do evil, as well as possibly encourage him to change his views due to his own desires for fame and fortune. Thus, if this were my motivation then my support for such a boycott would be moral, and perhaps even obligatory.
The use of economic force is then justified in the same manner as the use of other forms of force. Defending oneself and defending others are justifiable motivations, but using force based merely on a desire to injure someone you dislike is not morally acceptable.