Evidently the Yale Law Journal has begun putting some of their articles online. They have a really good article up entitled The Freedom of Imagination: Copyright's Constitutionality, about whether or not copyright (being, as it is, a major restraint on the exercise of free speech) is constitutional. The author decides copyright proper (that is, the parts that deal with unauthorized reproduction and distribution) are constitutional, but that the parts prohibiting derivative works may not be. To support the idea he puts forth a new logical basis for the First Amendment, which is that it is intended to protect the free exercise of imagination. His reasons for the basis are very interesting and, I think, quite persuasive. In fact, this seems like the best suggestion for balancing copyright with artistic interplay I've read yet.