A U.S. Court of Appeals for the Fifth Circuit judge seemed skeptical Wednesday of a new Medicare drug price negotiation program meant to lower prescription costs, which pharmaceutical manufacturers and related groups across the country are challenging as unconstitutional.

“This is challenging to a novel, unprecedented drug-price setting program in an industry that the government is the 800-pound gorilla [in], the purchaser with the most monopsony power in the United States,” Judge Jennifer Walker Elrod said during oral arguments in New Orleans.