One issue I have been following from the sidelines is the current dispute over the constitutionality of the Federal Trade Commission’s Do-Not-Call registry, which prevents those engaging in commercial telemarketing calls from making them to those on the list except in certain circumstances. The law has an exception for calls by charitable and political organizations, and a lower court has held that the law violates the First Amendment because it singles out some speech for protection but not others. It looks like a law professor’s ideal hypothetical to test the limits of the commercial speech doctrine (i.e., to what extent may the government regulate commercial speech more heavily, consistent with the First Amendment).
I have been hearing reports (and received an e-mail this morning) that one possible way around the First Amendment problem is to remove the exemption for charitable and political calls, and allow callers to “opt in” to receiving such calls. That appears to eliminate one First Amendment problem—it does not single out commercial speech for special treatment, but does it create another? Can the government tell those who wish to engage in election-related (or perhaps simply political) speech that they may not call people who say in advance that they don’t want to be contacted? I hope Eugene Volokh will chime in on this question.
UPDATE: Eugene responds via e-mail:

I think that if the government had a blanket prohibition on unsolicited calls, for political or other reasons, to anyone who has opted out (perhaps with an exception for people with whom you have a preexisting business or social relationship), this would be permissible. See Rowan v. Post Office Dep’t (upholding a law that let householders block future mail from particular senders); Martin v. City of Struthers (acknowledging that householders could put up “Do Not Soliciting” signs, even as to political solicitors, that the city could then enforce).

UPDATE II Eugene has posted more extensive comments here.