Among the groups signing the brief are the American Library Association (ALA), the Association of Research Libraries, the American Association of Law Libraries, the Medical Library Association and the Special Libraries Association. The American Civil Liberties Union, in one of the group's first forays into copyright law, has drafted the brief opposing the Motion Picture Association of America (MPAA) and the Recording Industry Association of America (RIAA).

A central argument of the brief is that the district court got it right when applying a 1984 Supreme Court decision to the Internet. That decision, Sony v. Universal City, said Sony could continue to manufacture its Betamax VCR because a company "cannot be a contributory (copyright) infringer if, as is true in this case, it has had no direct involvement with any infringing activity."