Nippon Steel and United States Steel claimed former President Joe Biden unfairly prejudged their $14.1 billion merger and gave the companies no chance for feedback on a "sham” national security review before he blocked the deal.

The steel makers, which sued last month, said in an opening brief Monday that the Committee on Foreign Investment in the United States violated their due process rights last year by allowing "virtually no substantive engagement” with the companies.

CFIUS, which is supposed to conduct an apolitical review to protect national security, ignored its procedures after Biden said in March 2024 he’d block the merger, the companies told a federal appeals court in Washington. They claim he did that to gain favor with union steelworkers in Pennsylvania while he was seeking re-election. The panel’s review spanned nine months before Biden formally blocked the deal in January, according to the court filing.