A U.S. appeals court last week ruled against the Environmental Protection Agency’s decision to deny biofuel blending waivers to small refineries.

Six small refineries sued EPA earlier this year after the agency denied almost all requests for small refinery waivers under the Renewable Fuel Standard (RFS). The refiners claimed the RFS requirement to blend a certain amount of biofuel into their products would cause them financial hardship. In July, the EPA denied 26 petitions from 15 small refineries for waivers for the 2016-2018 and 2021-2023 compliance years.

The challenge was brought by Wynnewood Refining, Ergon, Calumet Shreveport, and Placid Refining Company. In its 38-page decision, the court ruled that the EPA’s rejection of the waiver requests was “impermissibly retroactive; contrary to law; and counter to the record evidence.”