The U.S. Supreme Court dealt a major blow to the music industry Wednesday (March 25), ruling unanimously that internet service providers cannot be held liable for copyright infringement committed by their users, even when those providers were repeatedly warned that specific customers were illegally downloading pirated music.

Justice Clarence Thomas wrote the opinion for a unanimous court, siding with Cox Communications in a long-running legal battle against the nation's largest record labels, including Sony Music Entertainment.

The case centered on peer-to-peer file-sharing tools like BitTorrent, which allow users to download pirated music. The record labels argued that Cox, which provides internet access to more than six million homes and businesses, should have terminated the accounts of users it knew were repeatedly violating copyright law. Cox refused, and the labels sued.

A federal jury had previously sided with the labels, awarding them more than $1 billion in damages for the infringement of over 10,000 copyrighted works. An appeals court in Richmond, Virginia later tossed out that award, but still found Cox guilty of 'willful contributory infringement.' Cox then appealed that finding to the Supreme Court.

Cox argued that less than 1% of its users infringe on music copyrights and that its internal compliance measures "got 95% of that less than 1% to stop." The company warned the justices that a ruling against it would force ISPs to terminate entire households, hospitals, universities, and even regional internet providers all because of one alleged infringer on a shared connection.

The music labels pushed back hard. Their attorney, Paul Clement, argued that Cox effectively ignored the problem, noting that the company terminated 619,711 subscribers for non-payment over the same period it cut off just 32 for serial copyright abuse. The labels represent artists whose work includes music by Bob Dylan, Bruce Springsteen, Beyoncé, Eminem, and Gloria Estefan, among others.

The labels claimed Cox had a 13-to-14 strike policy for cutting off infringing customers, but ultimately "simply stopped terminating infringing subscribers."

During oral arguments in December, several justices expressed concern about the far-reaching consequences of siding with the labels. Justice Samuel Alito said of the music industry's position, "I just don't see how it's workable at all." Justice Sonia Sotomayor questioned the fairness of cutting off internet access for "50,000 or 100,000 people" because "one person in that region continues to infringe."

The case drew support for Cox from major tech companies, including Google and X, which argued that a ruling against the ISP could "wreak havoc" on the tech industry, including artificial intelligence platforms facing their own copyright challenges.

The ruling closes a years-long legal chapter for Cox, though the broader fight over online piracy and how much responsibility internet providers bear for their users' behavior is likely to continue in courts and in Congress.

Ross Kaminsky on the News with Jeana Gondek