An effort to block a Minnesota state mandate that requires all diesel fuel sold at the pump to be at least 10% biofuel has been blocked by a district court judge, according to the Minnesota Star Tribune.

In 2015, trucking groups within the state filed a lawsuit claiming the mandate conflicted with federal Clean Air and Renewable Fuels laws. The lawsuit was brought by the Minnesota Trucking Association, the Minnesota Automobile Dealers Association, Alliance of Automobile Manufacturers, American Petroleum Institute and American Fuel & Petrochemical Manufacturers.

The suit sought an injunction to block the mandate and a future increase to 20% biofuel. It argued that the mandate would result in higher maintenance costs and engine problems, as well as a safety hazard because older vehicles were not designed to run on biofuel blends of 10-20%.

The lawsuit also argued that the state was forcing fleets to purchase what is usually a more expensive fuel while denying access to fuels that were recommended for use in many vehicles.

However, the judge ruled the Clean Air Act did not pre-empt Minnesota’s mandate, and added that if the state mandate actually violated the Clean Air Act that the EPA would have filed its own injunction.

The Minnesota Trucking Association's president, John Hausladen, said the group was disappointed in the judgment and would consider what steps it should take next with the other plaintiffs in the case.