France’s top administrative court has overturned the French government’s decision last year to ban the sale of certain Mercedes vehicles in a dispute over air conditioning refrigerant.

Monday’s decision by France’s Conseil d’Etat cements the temporary injunction it granted in August to end a two-month freeze on sales of the German carmaker’s A-class, B-class, CLA and SL models after parent Daimler refused to stop using the R134a refrigerant that is being phased out by the European Union.

France’s Conseil d’Etat said in a statement that the ban imposed by France’s ecology minister was unjustified and that the vehicles had not been shown to present a serious threat to the environment.

R134a, a global warming agent 1,400 times more potent than carbon dioxide, had been banned from new vehicles since the start of 2013 under the terms of an EU directive, but Daimler said it had identified unacceptable safety risks in the alternative.

The only available substitute that meets EU requirements is R1234yf, made by Honeywell and Dupont.

Daimler has said it wants to switch to a CO2-based air conditioning system by 2017.