The Supreme Court is being asked to resolve a high-stakes battle over when Internet Service Providers (ISPs) can be held liable for their users’ copyright infringement. Two petitions — Cox Communications, Inc. v. Sony Music Entertainment (No. 24-171) and Sony Music Entertainment v. Cox Communications, Inc. (No. 24-181) — stem from a Fourth Circuit decision involving a $1 billion jury verdict against Cox for music piracy on its network. In November 2024, the Court invited the Solicitor General (SG) to weigh in. In late May 2025, SG John Sauer filed the government’s brief, recommending that the Supreme Court grant Cox’s petition to clarify—and ultimately narrow—the standard for contributory infringement.
For this post, I take a step back and talk through some of the legal doctrines at issue — contributory & vicarious liability — in the context of ISP copyright infringement and then delve into how they might apply in Cox.
Background: The litigation began when a consortium of record companies and music publishers (including Sony Music) sued Cox Communications for copyright infringement based upon actions by Cox’s internet subscribers. The alleged infringements occurred in 2013–2014, when Cox users engaged in massive peer-to-peer file sharing of music over networks like BitTorrent. At the time, anti-piracy agent, MarkMonitor, sent Cox hundreds of thousands of infringement notices identifying Cox subscribers by IP address. But, Cox’s internal policy was to follow an admittedly lax “thirteen-strike” system: repeat infringers would receive warnings and temporary suspensions, but Cox often declined to permanently terminate paying customers’ accounts. Evidence presented in the case showed Cox implemented its policy haphazardly—terminating only 33 subscribers for copyright abuse while tolerating many more—because it “wanted to avoid losing revenue” from monthly subscriber fees.
Cox’s inaction meant it forfeited the DMCA safe harbor that usually shields ISPs from monetary liability if they adopt and reasonably implement a policy to terminate repeat infringers. Without that safe harbor, the case proceeded under traditional secondary copyright liability doctrines. After a 12-day trial, a jury found Cox willfully liable for both contributory and vicarious infringement of 10,017 works and awarded the maximum statutory damages for willful infringement – totaling roughly $1 billion. The trial court upheld the verdict, and Cox appealed.
On appeal, the Fourth Circuit issued a split decision in February 2024. It affirmed Cox’s liability for contributory infringement but reversed on vicarious infringement, finding the evidence legally insufficient on that theory. The Fourth Circuit agreed that Cox knowingly contributed to its subscribers’ direct infringement by continuing to provide internet service to known repeat infringers, but it held that Cox did not derive the kind of direct financial benefit from infringement necessary for vicarious liability. Because it was unclear how the now-invalidated vicarious liability finding might have affected the jury’s damages award, the Fourth Circuit vacated the $1 billion award and remanded for a new trial on damages. Both sides then petitioned the Supreme Court: Cox, to challenge the contributory liability ruling (and the willfulness standard enhancing damages), and Sony, to challenge the vicarious liability ruling.
U.S. copyright law imposes liability not only on direct infringers but also on certain third parties who facilitate or benefit from direct infringement by others. The first approach – vicarious liability – is not IP specific, but rather is derived from agency doctrine in torts. Vicarious liability underlies most infringement claims, where the actions of a defendant’s employees are typically imputed to the employer. We formerly used the term “master-servant” as an important way to establish vicarious liability. Although that terminology is no longer used, the framework still requires looking for:
- Right and ability to supervise or control the direct infringer’s activities.
- A direct financial benefit derived from the infringement.
But, this can be established in a variety of ways, including the classic “dance hall” cases — where a venue owner can be held vicariously liable when patrons or performers infringed songs on its premises, because the owner had control over the premises and gained financially from the infringing performances (increased customer patronage). While the control and direct benefit can be difficult to establish, a key feature of vicarious liability is that it typically does not require knowledge of the copyright or the infringement.
Contributory infringement, on the other hand, requires a party to induce, cause, or materially contribute to another’s infringing activity, with knowledge of the infringement. Thus, someone who knows about ongoing infringement and actively helps make it happen can be on the hook for contributory liability. Patent law separates out active inducement, and that can certainly also form liability in copyright law (although there is no statute on point). In copyright law, we typically think of inducement as a form of contributory infringement.
In Cox’s case, there was no evidence that Cox encouraged customers to become pirates. Rather, the liability (if any) arise from their knowledge that their services were being used to infringe, and knowing failure to prevent that infringement.
The Digital Millennium Copyright Act of 1998 created a structured safe harbor (17 U.S.C. § 512) to protect online intermediaries from monetary liability for users’ infringements, provided they meet conditions like expeditiously removing infringing material upon notice and terminating repeat infringers in appropriate circumstances.
There is a bit of a circuit split on these issues — with what might be called the “simple measures test.” The Ninth Circuit asks whether there was some simple measure that the ISP could have taken to avoid the infringement. Under this test, a defendant will only be liable if it was aware of a simple measure to stop the infringement and still failed to act. The Fourth Circuit in this case did not require that instruction to the jury, making it seemingly more plaintiff friendly. Of course, this is not a very high bar – since it would have been very simple to terminate services to egregious repeat infringers — arguably the most straightforward measure an ISP could take and one that DMCA statute already suggests.
The Solicitor General’s recently filed amicus brief takes a clear position: Grant the adjudged infringer Cox’s petition (No. 24-171) to address and likely narrow contributory liability, and deny the copyright holder Sony’s cross-petition (No. 24-181), keeping vicarious liability narrow.
The SG’s petition takes a stronger position than any of the courts, arguing that any contributory liability standard must demand “conscious and culpable participation in the infringing conduct” by the defendant. Quoting dicta from Twitter, Inc. v. Taamneh, 598 U.S. 471 (2023). The brief particularly criticizes jury instructions in Cox’s trial regarding willful infringement (that triggered enhanced damages) by asking if Cox knew its subscribers were infringing rather than asking if Cox knew its own conduct was unlawful. On the vicarious liability front, the SG argues that the Fourth Circuit was correct in requiring proof that Cox derived a direct financial benefit from the infringement, and that general ongoing subscribers is not enough.
The next step in the case is for the Supreme Court to decide whether to grant review. Historically, the Court gives considerable weight to the SG’s recommendations in CVSG situations (though it is certainly not a guarantee). There is a good chance we’ll get an answer later this month.