Lockheed Martin Corp. retirees who worked at a nuclear plant in Hanford, Wash., can’t sue the federal government over an alleged pension cut.

The retirees don’t have an implied contract with the government that would allow them to sue under the Tucker Act, the U.S. Court of Appeals for the Federal Circuit ruled Jan. 9. The workers’ pension plan, which covered employees of contractors and subcontractors working at the Hanford plant, didn’t give rise to a contract binding the federal...