Opinion of the Court
fault than the mere understanding that some of one’s products will be misused. It leaves breathing room for innovation and a vigorous commerce. See Sony Corp. v. Universal City Studios, 464 U.S., at 442; Dawson Chemical Co. v. Rohm & Haas Co., 448 U.S. 176, 221 (1980); Henry v. A. B. Dick Co., supra, at 48.
The parties and many of the amici in this case think the key to resolving it is the Sony rule and, in particular, what it means for a product to be “capable of commercially significant noninfringing uses.” Sony Corp. v. Universal City Studios, supra, at 442. MGM advances the argument that granting summary judgment to Grokster and StreamCast as to their current activities gave too much weight to the value of innovative technology, and too little to the copyrights infringed by users of their software, given that 90% of works available on one of the networks was shown to be copyrighted. Assuming the remaining 10% to be its noninfringing use, MGM says this should not qualify as “substantial,” and the Court should quantify Sony to the extent of holding that a product used “principally” for infringement does not qualify. See Brief for Motion Picture Studio and Recording Company Petitioners 31. As mentioned before, Grokster and StreamCast reply by citing evidence that their software can be used to reproduce public domain works, and they point to copyright holders who actually encourage copying. Even if infringement is the principal practice with their software today, they argue, the noninfringing uses are significant and will grow.
We agree with MGM that the Court of Appeals misapplied Sony, which it read as limiting secondary liability quite beyond the circumstances to which the case applied. Sony barred secondary liability based on presuming or imputing intent to cause infringement solely from the design or distribution of a product capable of substantial lawful use, which the distributor knows is in fact used for infringement. The
