A billion-dollar lawsuit over music piracy must be reviewed by the U.S. Supreme Court, the Justice Department now says, warning that a “sweeping” ruling won by the record labels could force internet providers to cut off service to many Americans.

The massive copyright case – in which Universal Music Group, Sony Music Entertainment and Warner Music Group won a $1 billion verdict in 2019 – saw a lower court hold Cox Communications itself liable for widespread illegal downloading by its users.

But in a brief filed Tuesday, Solicitor General D. John Sauer says the justices must consider overturning that ruling – telling the high court that the “sweeping” decision conflicts with legal precedent and has “broad practical implications” for how Americans use the internet.

“Losing internet access is a serious consequence, as the internet has become an essential feature of modern life,” the solicitor general writes. “And because a single internet connection might be used by an entire family—or, in the case of coffee shops, hospitals, universities, and the like, by hundreds of downstream users—the decision below could cause numerous non-infringing users to lose their internet access.”

The central problem with the ruling against Cox, the feds say, is that it imposes costly liability on an internet service providers (ISPs) simply because “the music industry sends notices alleging past instances of infringement by those subscribers.” They say that approach could force IPSs to take aggressive measures out of fear of billion-dollar verdicts.

“Given the breadth of that liability, the decision below might encourage providers to avoid substantial monetary liability by terminating subscribers after receiving a single notice of alleged infringement,” Sauer writes.

An attorney for the labels did not immediately return a request for comment. In previous filings, lawyers for the music companies have rejected such dire warnings, calling them “contrived” and “disingenuous” efforts to avoid legal liability.

UMG, Warner and Sony all sued Cox in 2018, seeking to hold the internet giant itself liable for alleged wrongdoing committed by its users. The labels said Cox had ignored hundreds of thousands of infringement notices and had never permanently terminated a single subscriber accused of stealing music.

ISPs like Cox are often shielded from such lawsuits by the Digital Millennium Copyright Act, or DMCA. But a judge ruled that Cox had forfeited that protection by failing to terminate people who were repeatedly accused of violating copyright law. Stripped of that immunity, jurors held Cox liable in December 2019 for the infringement of 10,017 separate songs and awarded the labels more than $99,000 for each song — adding up to a whopping $1 billion.

Earlier this year, a federal appeals court ordered the award recalculated earlier this year, ruling that aspects of the verdict were improper. But the appeals court also upheld other parts, and Cox is still facing the potential of a very large penalty when it is re-issued.

So Cox took the case to the Supreme Court in August, warning that the “draconian” approach to copyright law “threatens mass disruption” for internet users: “This court should grant certiorari to prevent these cases from creating confusion, disruption, and chaos on the internet. Innovation, privacy, and competition depend on it.”

Those same arguments are echoed by the solicitor general’s Tuesday brief to the justices, albeit in more subdued terms.

The appellate court ruling against Cox “departs from this court’s contributory-infringement precedents,” Sauer writes, including the landmark 2005 ruling that shuttered filesharing websites like Grokster. The feds say it also conflicts with a more recent ruling that said Twitter didn’t aid a terrorist attack simply because ISIS used the social media site.

“Adoption of Sony’s rule would … threaten liability for other service providers (e.g., an electric utility) that might be asked to cut off service to identified customers who had previously used the service for unlawful purposes,” Tuesday’s filing.

Attorneys for the labels will have a chance to file their own brief responding to the government’s arguments. In their own motion asking the Supreme Court to reject Cox’s appeal, the music companies said the ISP was exaggerating such warnings to help its legal case.

“Cox has no problem severing the internet lifeline for tens of thousands of homes and businesses when its own revenue is on the line,” the labels wrote in a November response. “Cox terminated over 600,000 subscribers for failure to pay their bills during the two-year period relevant here. During that same period, it terminated 32 subscribers for copyright infringement.”