Judges at the Federal Administrative Court in Leipzig found that local authorities have the right to enforce bans on older, dirty diesels from their city centres plunging millions of drivers into uncertainty.
The court did not however impose such bans itself, leaving that up to city and municipal authorities. The judges did however urge them to “exercise proportionality” in enforcing the bans.
The case centred around the smog-clogged cities of Stuttgart and Duesseldorf, but could have nationwide repercussions.
The outcome marks a major victory for the environmentalist group Deutsche Umwelthilfe (DUH), which sued Stuttgart and Duesseldorf to force them to take action against the toxic nitrogen oxides and fine particles emitted by older diesel engines.
Lower-level judges had already backed their demand for driving bans but the states of Baden-Wuerttemberg and North Rhine-Westphalia appealed the rulings, saying such curbs should be decided at the federal level.
That appeal has now failed, as judges at the nation’s top administrative court again sided with the environmental campaigners.
“It’s a great day for clean air in Germany,” said DUH chief Juergen Resch.
In their ruling, the judges said any diesel bans should be imposed gradually, with exceptions granted to certain vehicles.
In Stuttgart, a diesel ban could be enforced in September at the earliest.
In a nod to concerns that the bans could slash the resale value of millions of older diesels, presiding judge Andreas Korbmacher said “certain losses will have to be accepted”.
He also urged city and municipal authorities to avoid “a patchwork” of local measures.
Critics had earlier argued that the bans would be complicated to enforce and cause confusion among drivers.