Major tech companies are weighing in on a high-profile climate case in support of EPA greenhouse gas regulations. Apple, Amazon, Google, Meta, Microsoft, Netflix, Tesla, Paypal, and Salesforce are among the companies that filed a brief yesterday asking the Supreme Court to uphold the agency’s authority to regulate the pollution causing climate change.

“Both corporate action and EPA regulation are needed to reduce emissions at the rate necessary to avoid the worst impacts of climate change,” the brief says. The companies say they are “united in their efforts to combat this threat.”

The case the companies are weighing in on, West Virginia v. EPA, concerns whether or not the EPA has the regulatory authority to limit greenhouse gas emissions from power plants through the Clean Air Act. The Supreme Court agreed to hear the case last year after it was brought by coal companies and states friendly to the fossil fuel industry.

It’s the latest escalation of a regulatory battle that started during the Obama administration. That’s when the EPA established the Clean Power Plan (CPP), which would have forced power plants to rein in the planet-heating pollution they produce when burning fossil fuels. After facing a flurry of legal challenges, the Supreme Court issued a stay on implementing the plan in 2016.

Then the Trump administration repealed the Obama-era plan and replaced it with its own, called the Affordable Clean Energy Rule (ACE). It was a much weaker proposal that would have done little to cut the US’s carbon dioxide emissions and was expected to result in upwards of 1,400 more premature deaths related to air pollution. A federal court ultimately struck down ACE, so it was never implemented either.

That gives the Biden administration the opportunity to write up its own greenhouse gas regulations. Joe Biden has already committed to slashing US greenhouse gas emissions roughly in half from peak levels under the Paris Agreement. Accomplishing that will require sweeping policy changes, which his administration has so far struggled to enact through legislation. Agency rule-making is another way that the administration can help drive down emissions across the economy, although as the legal back-and-forth over the CPP and ACE show, it will be difficult to achieve climate goals through regulation alone. If the Supreme Court sides with the states challenging EPA’s regulatory authority, that would make meaningful climate progress through agency regulations even harder.

Tech companies in the brief argue that action by the EPA would help them by creating more regulatory certainty at the federal level. They also say that EPA rules on climate pollution would encourage clean energy development, which the companies need to reach their own climate goals.

While each of the companies has adopted its own sustainability targets, several — including Amazon, Google, and Meta — have been called out for continuing to do business with fossil fuel companies. Activists have also called on the companies to back up their climate commitments with lobbying for policies to slash pollution.

The Supreme Court is supposed to start hearing arguments in West Virginia v. EPA in February. But stakeholders, including tech companies that have made recent commitments to tackle climate change, are already clamoring to be heard.