The American Conservative Union and the National Taxpayers Union have this to say in their brief [PDF] about the dangers (to podcasting, among other things) of judges expanding the reach of copyright's statutory monopoly:
Petitioners seek, in effect, a declaration that peer-to-peer file-sharing technologies are within their statutory copyright monopoly, that they can exclude others from distributing these technologies, and that, therefore, the developers and distributors of these technologies must obtain Petitioners' permission before distributing any such services or systems. The Court should see this for what it is—an attempt to leverage a lawful, but statutorily limited, monopoly over the distribution of expressive "works of authorship" into an unwarranted and anti-competitive monopoly over the distribution of innovative technologies.
Podcasting, of course, is merely one of innumerable examples of innovative technology that builds upon, and interacts with, the peer-to-peer distribution networks of the kind that Respondents have enabled. Millions of Americans are engaged in the business of building, developing, and using these technologies, and every one of them—every podcaster, every potential podcaster, every potential consumer of podcasting services, and every owner of an iPod or other mobile digital audio device—has a real and concrete stake in this llitigation, an interest that the Court must take into account.
In many ways, peer-to-peer technology is the printing press of the internet in distributing massive amounts of information quickly and cheaply to the world, and First Amendment rights are at stake. ... Citation of alleged copyright infringment by some users of the printing press is not justification for shutting down all presses, and certainly not before their powerful legitimate uses become fully apparent.
Legislating from the bench is unjustified in general, and is particularly ill-suited to new technologies that facilitate constitutionally protected speech and association.