the file sharing companies, while the RIAA and MPAA both sided with MGM and the other entertainment companies. Napster, having lost its similar lawsuit about its enabling of users' copyright infringement, filed a brief in support of the entertainment companies. Billionaire Mark Cuban partially financed Grokster's legal battle. Oral arguments During oral argument, the Supreme Court justices appeared divided between the need to protect new technologies and the need to provide remedies against copyright infringement. Justice Antonin Scalia expressed concern that inventors would be chilled from entering the market by the threat of immediate lawsuits. Justice David Souter questioned how the interpretation of the law the plaintiffs argued for would affect devices like copy machines or the iPod. The music industry suggested that iPods have a substantial and legitimate commercial use in contrast to Grokster, to which Souter replied, "I know perfectly well that I can buy a CD and put it on my iPod. But I also know if I can get music without buying it, I'm going to do so." On the other hand, the justices seemed troubled at the prospect of ruling that Grokster's alleged business model of actively inducing infringement and then reaping the commercial benefits was shielded from liability. Opinion of the Court The opinion of the court was authored by Justice Souter, who wrote: "We hold that one who distributes a device with the object of promoting its use to infringe copyright, as shown by clear expression or other affirmative steps taken to foster infringement, is liable for the resulting acts of infringement by third parties." While the Court unanimously held that Grokster could be liable for inducing copyright infringement, concurring opinions by several of the Justices showed considerable disagreement over whether the case is substantially different from the Sony precedent, and whether that precedent should be modified. On the one hand, Justice Ginsburg, joined by Kennedy and Rehnquist, claimed that "[t]his case differs markedly from Sony" as there was insufficient evidence of non-infringing uses of the technology. On the other hand, Justice Breyer, joined by Stevens and O'Connor, claimed "a strong demonstrated need for modifying Sony (or for interpreting Sony's standard more strictly) has not yet been shown," primarily because "the nature of ... lawfully swapped files is such that it is reasonable to infer quantities of current lawful use roughly approximate to those at issue in Sony." These justices concurred in the