The US Supreme Court has just told copyright owners to stop trying to turn broadband into a deputised enforcement squad.
In a 7-2 ruling on Wednesday, the court reversed the Fourth Circuit and held that Cox Communications is not contributorily liable for subscribers’ copyright infringement unless the service was meant to be used that way.
US Supreme Court justice Clarence Thomas wrote: “Contributory liability cannot rest only on a provider’s knowledge of infringement and insufficient action to prevent it.”
The case, Cox Communications, Inc. v. Sony Music Entertainment, started when Sony Music and other major rights holders sued Cox in the Eastern District of Virginia. Sony hired MarkMonitor to watch file-sharing activity and, over a roughly two-year period, it fired off 163,148 infringement notices to Cox.
A jury sided with Sony on contributory and vicarious liability, calling Cox’s infringement wilful and slapped it with $1 billion in statutory damages. The Fourth Circuit upheld contributory liability, saying that “supplying a product with knowledge that the recipient will use it to infringe copyrights is exactly the sort of culpable conduct sufficient for contributory infringement.”
Cox took it to the Supremes and, in an opening brief filed in August 2025, said the Fourth Circuit “flouts a century of this Court’s case law” by imposing liability without proper culpable conduct. Cox warned against turning ISPs into “internet police.”
The US solicitor general was allowed to join oral argument as an amicus at the 1 December hearing. US Supreme Court Justice Sonia Sotomayor described the parties’ positions as two “extremes” and pushed for a rule that addresses both ends of the spectrum.
Thomas’s majority opinion leaned on a basic point that tends to ruin a good rights-holder narrative. The “Copyright Act does not expressly render anyone liable for infringement committed by another.”
The court said contributory liability needs intent, not just awareness. A copyright owner can show that intent by proving affirmative inducement or by showing a service was built or tailored for infringement, and the majority said Cox did neither.
On inducement, the court said Cox did not “induce” or “encourage” infringement, and Sony produced no “evidence of express promotion, marketing, and intent to promote infringement.” The court highlighted Cox’s warnings, suspensions, and terminations as repeated discouragement, not a wink-and-a-nod.
On “tailored to infringement”, the majority pointed to the obvious, which is that internet access is used for practically everything. Cox’s service was “capable of ‘substantial’ or ‘commercially significant’ noninfringing uses,” so it did not fit the narrow bucket Sony wanted.
The justices rejected the Fourth Circuit’s knowledge-plus-not-enough-action theory, warning it runs past established secondary liability doctrine. The court pointed back to cases such as Metro-Goldwyn-Mayer Studios Inc. v. Grokster, Ltd. and Sony Corp. of America v. Universal City Studios, Inc., then repeated the line rights holders hate: “contributory liability cannot rest only on a provider’s knowledge of infringement and insufficient action to prevent it.”
Sony tried a different angle by leaning on the Digital Millennium Copyright Act safe harbour, arguing it becomes pointless if ISPs can keep serving known infringers without paying. The court said Sony was overreading the DMCA, which creates new defences rather than sneaking in a new duty to kick customers off the internet.
Sotomayor, joined by Justice Ketanji Brown Jackson, concurred only in the judgment and took a swipe at the majority for tightening the screws too far. She said precedents leave room for “other common-law theories, such as aiding and abetting, could apply in the copyright context.”
“The majority’s limiting of secondary liability here dismantles the statutory incentive structure that Congress created,” she said.
