Grokster, Ltd., distributed free software that could be used to download files from the Internet. Frequently, this software was used to illegally download copyrighted material. MGM Studios sued Grokster, alleging that Grokster had marketed its software for the purpose of sharing copyrighted files. There was also evidence that Grokster made no attempt to prevent or discourage copyrighted material from being transferred.

Grokster made no money from the file transfers themselves; rather, its income came from advertising sold on its Web site. Grokster moved for summary judgment on the basis that its software could be legitimately used to transfer noncopyrighted works. The U.S. District Court ruled for Grokster on its motion for summary judgment. The Court of Appeals upheld the ruling.

The Supreme Court vacated the motion for summary judgment and remanded for further proceedings. What do you think the Court's reasoning behind this decision was?