What happens when a major global power—one that will soon boast the world’s largest economy to boot—refuses to accept legally “binding” arbitration decisions? We’re about to find out.

A tribunal in The Hague ruled unanimously on a hotly contested territorial dispute between the Philippines and China on Tuesday. Beijing got beaten—badly. The panel ruled that China’s expansive territorial claims to some 90 percent of the South China Sea—enforced through the so-called Nine Dash Line—are illegitimate. It also rebuked Beijing for its aggressive construction of artificial islands throughout the region.