SWIPLit
Knowledge is Not Complicity: Cox Communications v. Sony Music Entertainment
On March 25, 2026, the Supreme Court unanimously held in Cox Communications, Inc. v. Sony Music Entertainment that an internet service provider does not commit contributory copyright infringement by providing internet service to subscriber accounts it knows to be associated with infringement. Reversing the Fourth Circuit, the Court held that contributory liability requires proof that the ISP intended its service to be used for infringement and that such intent can be shown through either inducement or by providing a service tailored to infringement purposes.
Cox Communications is one of the nation’s largest ISPs, with approximately six million subscriber accounts. Sony Music Entertainment and several other music copyright owners hired MarkMonitor to detect infringing activity across the internet and trace it to specific IP addresses. During a roughly two-year period, MarkMonitor sent Cox 163,148 notices identifying IP addresses associated with infringing activity. Cox maintained a graduated response system that sent warnings, suspended service, and ultimately terminated accounts after repeated warnings. Every subscriber was also contractually prohibited from transmitting infringing content.
Rather than sue individual infringers, Sony sued Cox in the Eastern District of Virginia. The court held Cox liable for willful contributory infringement of 10,017 copyrighted works and awarded Sony $1 billion in statutory damages. The Fourth Circuit affirmed, reasoning that supplying a service with knowledge that it will be used to infringe is sufficient culpable conduct. The Supreme Court granted certiorari.
The Copyright Act does not expressly render anyone liable for another’s infringement, but the Supreme Court has recognized two categories of secondary liability: vicarious liability and contributory liability. The second, contributory liability, was the doctrine at issue in the case and comes from two prior Supreme Court decisions. In Sony Corp. of America v. Universal City Studios, Inc., 464 U.S. 417 (1984), the Court held that selling a product capable of substantial noninfringing uses does not make a manufacturer contributorily liable even if the product is also used to infringe. In Metro-Goldwyn-Mayer Studios, Inc. v. Grokster, Ltd., 545 U.S. 913 (2005), the Court held that affirmatively marketing a service as a piracy tool does establish the requisite intent. Together, these decisions provide that contributory liability turns on intent, which is shown either through (a) actively inducing infringement or (b) by providing a service with no substantial noninfringing use.
Writing for seven justices, Justice Thomas applied this framework and held neither element satisfied. First, the Court reasoned Sony “provided no ‘evidence of express promotion, marketing, and intent to promote’ infringement,” and Cox’s graduated warning system reflected active discouragement of it. The Court further reasoned that general-purpose internet access plainly qualifies as a service capable of substantial noninfringing uses. The Court held that the Fourth Circuit’s “mere knowledge” standard, therefore, “went beyond the two forms” of recognized liability.
The Court further rejected Sony’s argument concerning the safe harbor provisions of the DMCA, which it argued were enacted to incentivize ISPs’ cooperation with copyright holders by adopting repeat-infringer termination policies. Sony argued that the safe harbor provisions would be rendered meaningless if ISPs faced no liability for serving known infringers in repeat instances of infringement. The Court held the DMCA “merely creates new defenses from liability for such providers”; it does not itself impose liability, and failure to qualify under the safe harbor does not bar a separate defense that the ISP’s conduct was non-infringing to begin with.
Justice Sotomayor, joined by Justice Jackson, concurred in the judgment but argued the majority “unnecessarily limits secondary liability even though this Court’s precedents have left open the possibility that other common-law theories of such liability, like aiding and abetting, could apply in the copyright context.” She further warned that by making knowledge-plus-continued-service insufficient, the majority “upends the statutory incentive structure that Congress created” and eliminates the incentives for ISPs to implement anti-infringement measures to qualify for DMCA safe harbor protection. Nonetheless, she agreed Cox prevailed on the facts presented because the notices Cox received identified only the IP address used, and not the actual infringer. The concurrence explained this gap from IP address to infringing user was insufficient to prove the specific intent element required to prove liability for common law aiding-and-abetting.
The holding is narrow and fact-specific, and the Court left open the possibility that knowingly providing service to repeat infringers could establish secondary liability under different circumstances. Providers should continue maintaining clear acceptable-use policies and graduated response mechanisms. Providers should also avoid any conduct that could be construed as affirmatively encouraging infringement or designing services to facilitate it, as those remain the two recognized paths to contributory liability.
