who "actively induces infringement of a patent" is "liable as an infringer," 35 U.S.C. § 271(b), just like someone who commits the underlying infringing act by "us[ing]" a patented invention without authorization, id. § 271(a). In contrast, someone who merely "sells … a material or apparatus for use in practicing a patented process" faces only liability as a "contributory infringer." Id. § 271(c). If Congress had meant to assign direct liability to both the person who actually commits a copyright-infringing act and any person who actively induces that infringement, the Patent Act tells us that it knew how to draft a statute that would have this effect. Because Congress did not do so, the Sony Court concluded that "[t]he Copyright Act does not expressly render anyone liable for infringement committed by another." 464 U.S. at 434. Furthermore, in cases like Sony, the Supreme Court has strongly signaled its intent to use the doctrine of contributory infringement, not direct infringement, to "identify[] the circumstances in which it is just to hold one individual accountable for the actions of another." Id. at 435. Thus, although Sony warns us that "the lines between direct infringement, contributory infringement, and vicarious liability are not clearly drawn," id. at 435 n.17 (internal quotation marks and citation omitted), that decision does not absolve us of our duty to discern where that line falls in cases, like this one, that require us to decide the question.
The district court apparently concluded that Cablevision's
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