A 123-year-old steelmaker’s fate could yet become a restraint on modern-day executive power. United States Steel and suitor Nippon Steel have gone to court over U.S. President Joe Biden’s decision to nix their $15 billion deal.

The Japanese firm’s planned purchase of its U.S. rival was blocked last week by President Joe Biden after a year of diplomatic tension, political debate and lobbying efforts from the companies and unions. Biden, who had previously said he opposed the tie-up, cited national-security risks, despite Japan being a close ally.