The European Court of Justice ruled on Thursday (17 December) that it had been illegal for car companies to install devices to defeat emissions tests and mislead motorists about diesel pollution levels.
“A manufacturer cannot install a defeat device which systematically improves, during approval procedures, the performance of the vehicle emission control system and thus obtain approval of the vehicle,” the court said.
The statement identified the manufacturer subject to the complaint as “Company X”, but the case is understood as relating to the “Dieselgate” scandal at German car giant Volkswagen (VW).
The VW group – whose subsidiaries include Porsche, Audi, Skoda and Seat – admitted in September 2015 that it had installed software to rig emissions in 11 million diesel vehicles worldwide.
Two VW employees have been sentenced to jail in the United States, as cases linked to the scandal spread around the world, and four former executives and engineers from the group are now on trial in Germany.
In the latest case, French prosecutors conducted an investigation and referred their findings to the ECJ, seeking clarifications of EU law.
The court found that the company had installed software in the cars that only recorded emissions levels in the vehicle when it was being driven in similar conditions to those when it was initially tested and approved.
It rejected the argument that the device could help protect the engine from wear and tear over time, since its main purpose was to skew emissions readings.
“In order to be justified, the presence of such a device must allow the engine to be protected against sudden and exceptional damage,” the statement said.
“A defeat device which systematically improves, during approval procedures, the performance of the vehicle emission control system… and thus obtains approval of the vehicle cannot come within the scope of the exception to the prohibition on such devices provided for by the regulation.”