Normally, Americans have a constitutional right to anonymous political activity. Indeed, the organizers of boycotts do not have to disclose their financiers. In the 1950s and '60s, protection of privacy and anonymity of donors was instrumental to the ability of the NAACP to operate in the South.
But in 1976 the Supreme Court allowed the government to require limited disclosure of political campaign giving. Increasingly, however, mandatory disclosure of political activity is not being used for any of the three legitimate state interests recognized by the court—exposing corruption, assisting in enforcement of other campaign-finance laws, or providing information that can help the public evaluate the message. Rather, compulsory political disclosure is increasingly used for organizing secondary boycotts of speakers. As one anti-Prop 8 activist cheered, "Years ago we would never have been able to get a blacklist that quickly!"
People have a right not to do business with companies or individuals. But blacklists—never a healthy part of political debate—endanger the very commerce that enriches us all.