The United Steelworkers’ opposition to the sale of U.S. Steel was dealt a setback after an arbitration panel ruled Nippon Steel sufficiently complied with the union’s contract to become the storied steelmaker’s new owner. The union filed a grievance earlier this year alleging that Nippon Steel hadn't met the requirements and obligations of its labor agreement with U.S. Steel, which runs into 2026. The three-member arbitration panel determined that Japan’s Nippon Steel provided assurances and showed the financial capability to comply with the contract, U.S. Steel said.