A federal appeals court has reinstated an antitrust complaint against a milk processor, ruling that the trial judge used the wrong standard for excluding an expert witness.

On Friday in Food Lion LLC v. Dean Foods Co., the U.S. Court of Appeals for the Sixth Circuit remanded the case to Eastern District of Tennessee U.S. District Judge Ronnie Greer. Retailers Food Lion and Fidel Breto filed the action over milk they bought from defendants Dean Foods and the National Dairy Holdings partnership of processing plants.