The US Supreme Court Monday rejected two appeals from Volkswagen AG, the German automobile manufacturer, regarding emissions tampering. The justices sought the views of the federal government, and, after review, turned down the cases of both Volkswagen Group of America, Inc. v. EPA of Hillsborough County, Florida and Volkswagen Group of America, Inc. v. Ohio, ex rel. Dave Yost, Attorney General.

Volkswagen claimed in both of the current appeals that the Clean Air Act provides protection for automobile manufacturers from state and local liability over updating vehicle emission testing systems. Volkswagen argued that the rebuttals from the states of Florida and Utah, using laws that bar tampering with emissions systems, were one-sided and that their vehicle software updates continually reduce emissions.

The rejection comes following a recommendation from the Biden administration urging the justices to review the lower court’s decisions. Both the Ohio Supreme Court and the US Court of Appeals for the Ninth Circuit ruled that anti-tampering laws could be enforced with regard to already-sold cars being driven on the roads. The situation would be different had the vehicles not been post-sale, which the Clean Air Act expressly preserves state and local authority over.

These appeals stem from the ongoing allegations that Volkswagen violated the Clean Air Act through the sale of around 600,000 diesel motor vehicles between 2009 to 2016, that were equipped with “defeat devices”. The “defeat devices” are a type of computer software designed to cheat on federal emissions tests, specifically in regards to oxides of nitrogen. Emission tests are designed to measure levels of pollutants – which include oxides of nitrogen – in vehicle exhaust.

In 2017, the US District Court for the Northern District of California granted a class-action settlement against Volkswagen for its use of “defeat devices” in their “clean diesel”-branded vehicles. The settlement came after evidence showed that Volkswagen used defeat devices to evade both the EPA and local emission test procedures. The device “sense[d] whether the vehicle is undergoing testing and produce[d] regulation-compliant results,” and it was the only way the company was able to obtain passing results. The vehicles released nitrogen oxides at up to 40 times over the permitted limit.

In the Ninth Circuit’s ruling, the court recognized that their result “may result in staggering liability for Volkswagen. But this result is due to conduct that could not have been anticipated by Congress: Volkswagen’s intentional tampering with post-sale vehicles to increase air pollution.”