Leipzig, Germany – Environmental bans on diesel-powered vehicles are legal in German municipalities, a top German court ruled on Tuesday, in a verdict that could have wide-ranging effects on the nation's automotive industry.

The ruling only specifically touches on the cities of Dusseldorf and Stuttgart, which sought to interpret German law so they could implement diesel bans in an effort to clean up polluted air.

Possible consequences for auto makers

But the ruling could have a wider effect and clear the way for other cities to impose limits on diesel use. That could carry consequences for Germany's large auto industry, which has relied greatly on diesel-powered vehicles.

Diesel power has become controversial ever since it emerged in 2015 that carmaker Volkswagen, and subsequently other manufacturers, had doctored test results to downplay the emissions released by diesel-powered engines.

"As of today, we have achieved diesel vehicle bans," said Juergen Resch, head of the environmental group Deutsche Umwelthilfe (DUH), which was also a party to the complaint.

Exceptions expected

Although the court approved the principle of diesel bans, it did tell the two cities to review their clean air plans to make sure they comply with guidelines, the Federal Administrative Court ruled. Stuttgart was cautioned to make sure any bans did not affect newer cars exempt from such actions. Dusseldorf was told to make sure a car ban was the only effective solution.

Stuttgart plans to introduce its ban no earlier than September 1, and allow exceptions for a variety of vehicles, including ones used by tradespeople.

However, the court did not require cities implementing bans to compensate drivers who must suddenly keep their vehicles outside city limits.

"Certain losses in value are to be expected," said presiding Judge Andreas Korbmacher.

He also urged German municipalities to work together on the bans and any other clean air guidelines, to avoid a "patchwork" of rules that would make it hard for German motorists and businesses to operate vehicles in multiple cities.

Tuesday's ruling builds on district court rulings that municipalities need more powers to ensure clean air and that vehicle bans might be the best way to implement them. Those rulings had been reversed by state courts, which had found that the attempt to ban diesel could not be made without the passage of a new federal law.

Diesel fumes contribute to pollution

Air pollution has become a growing problem in German cities, with much of the focus on nitrogen oxides (NOx), which can cause a variety of health problems affecting breathing and the circulatory system.

Vehicular traffic is responsible for 60 per cent of this pollution and diesel cars, which are popular in Germany, are a major portion of that.

Upper limits on the amount of such gases allowed in the atmosphere have been in place since 2010, but not universally enforced, despite lobbying efforts by environmental groups and actions by cities like Dusseldorf and Stuttgart.

The European Union has also pressured Germany to clean up its air. An EU court case also threatens if Germany does not take action quickly enough to clean up its air.

Germany's federal government is considering changes to traffic law that would give municipalities new rights to create traffic bans.

Cities pushing such bans have called on the government to implement the use of the Euro 6 blue disc, a standardized guide to show which vehicles meet the latest EU emissions standard. So far, Berlin has tried to stop that system from taking root in Germany.