Cox v. Sony: The Supreme Court’s Quest for a Contributory Infringement Standard

The U.S. Supreme Court seems likely to shake up American copyright law by articulating a different—and likely a stricter—legal standard for what constitutes contributory copyright infringement in the Cox Communications v. Sony Music Entertainment case.

During the December 2025 oral argument, none of the Justices seemed satisfied with the standard articulated by the Fourth Circuit Court of Appeals, which upheld a jury finding that Cox was a contributory infringer because it continued to provide service to accounts when it knew, based on repeat notices of past infringements, that some users of those accounts were almost certain to engage in future infringements. That court concluded that Cox had thereby knowingly made a material contribution to those infringements.

One problem for Sony is that the U.S. copyright statute, unlike its counterparts in patent and trademark laws, does not have a contributory infringement provision. The sole statutory hook for secondary copyright infringement is the provision that gives authors exclusive rights to do “or to authorize” certain acts, such as reproducing protected works in copies.

If authorizing infringement is the sole basis on which secondary copyright liability can be imposed, Sony would lose its case against Cox. Sony cannot show that this broadband provider authorized any of its subscribers to infringe music copyrights.

The Court has sometimes declined to uphold secondary liability claims in non-copyright cases when statutes are silent about it. But during oral argument, the Justices seemed to accept that secondary infringement can be established in copyright cases based on common law principles, as it previously held in Sony v. Universal (which concerned sales of infringement-enabling technologies) and MGM v. Grokster (which concerned peer-to-peer file sharing).

In Sony and Grokster, the Court borrowed secondary liability standards from U.S. patent law, citing to the “historic kinship” of U.S. copyright and patent laws and the careful Congressional balancing of interests in crafting patent secondary liability rules.

Patent law’s contributory infringement standard outlaws technologies that lack substantial non-infringing uses. Because Sony’s Betamax machines had and were capable of substantial non-infringing uses, such as making time-shift copies of broadcast television programs, Sony was not liable for contributory infringement by selling video tape recorders to the public, even though it had constructive knowledge that some (and perhaps many) customers would use these machines to make infringing copies of Universal’s movies.

In Grokster, the Court also looked to patent rules when deciding whether two peer-to-peer file sharing platforms were secondarily liable for their users’ infringements. It adopted patent law’s active inducement of third party infringements rule. Because the record was replete with evidence that Grokster and Streamcast had actively encouraged its users to infringe copyrights, MGM persuaded the Court that these developers could be held secondarily liable for their users’ infringements.

If the Court in Cox looks to patent law’s secondary liability doctrines, Cox would likely prevail in its appeal of the billion dollar judgment Sony got against it. Sony has not claimed that Cox induced infringement, nor that its technology lacks substantial non-infringing uses. There is no further basis for secondary liability in patent law.

Sony’s lawyer argued that the Court should look to trademark’s secondary liability rules which support its theory that making material contributions to infringement with knowledge that one’s acts are contributing to infringement suffices. However, the Court has twice before in Sony and Grokster declined to apply trademark secondary liability rules in copyright cases. The existence of substantial non-infringing uses of Cox’s internet services is a further reason not to look to trademark law.

Common law secondary liability rules may also be relevant in Cox. In one important case, Twitter v. Taamneh, decided in 2023, the Court recognized that the provider of a general purpose communication service (Twitter’s social media platform) should not be held liable for aiding and abetting some of its customers’ unlawful acts (terrorist attacks) unless the service engaged in purposeful culpable conduct that substantially assisted its users’ unlawful acts. The Court distinguished between nonfeasance and malfeasance, deciding that only the latter constituted actionable conduct.

Cox and the Solicitor General (whose amicus brief supported Cox’s appeal) urged the Court to apply Twitter ‘s secondary liability standard. Cox argues that, like Twitter, it provides a general communication service to the public. Sony has not shown that it engaged in purposeful, culpable conduct that substantially assisted infringement by users of its service. Sony argued that Twitter has no bearing on its copyright claims against Cox.

While some Justices were inclined to interpret secondary copyright liability narrowly, such as by borrowing from patent law or looking to the Twitter standard, other Justices worried that if Cox prevails, it would have no incentive to cooperate with copyright owners to reduce infringements.

A complicating factor in Cox is that many accounts flagged as repeat infringers are owned by institutions, such as universities, hospitals, and military barracks. Sony’s theory of liability, which is premised on Cox’s failure to terminate accounts of repeat infringers, would likely result in its terminating broadband services for institutions whose users were repeat infringers. This would have devastating consequences for many innocent persons who rely on access to the Internet through these institutions.

Based on the Cox oral argument, a blanket affirmance for Sony seems unlikely. The Court has two principal options. It may rule that as a matter of law, Cox cannot be held secondarily liable for users’ infringements because Sony cannot show it purposely engaged in culpable conduct. Or the Court may articulate a standard for contributory copyright infringement liability and remand the case to lower courts to consider whether Sony can prevail under that standard. Yet, what that standard will be is anybody’s guess.

Photo by Viktor Forgacs on Unsplash