Mealey's (December 23, 2022, 1:28 PM EST) -- CINCINNATI — The 3M Co. and others have filed their opening brief in the Sixth Circuit U.S. Court of Appeals, contending that it should reverse a lower court’s decision granting class certification to plaintiffs who say they have been injured by exposure to the firefighting agent known as aqueous film forming foam (AFFF) because the class is “novel and sprawling,” and it is “predicated on a questionable theory of standing.”...