Since its inception in 1995, the World Trade Organization’s (WTO) dispute settlement mechanism has resolved an impressive number of trade disputes and has earned a reputation as the “crown jewel” of the global trading system. Today, however, the mechanism is in crisis. WTO members have failed to negotiate updates to the rulebook, including rules on dispute settlement itself. As a result, the WTO Appellate Body increasingly is asked to render decisions on ambiguous or incomplete WTO rules. Its interpretations of such provisions have provoked charges by the United States and others that binding Appellate Body rulings, which establish precedents for future cases, effectively circumvent the prerogative of member countries to revise the WTO rulebook and thus undercut the national sovereignty of WTO members. For the past few years, US officials have blocked appointments of Appellate Body members to force WTO members to negotiate new rules that address US concerns and limit the scope for judicial overreach. If this problem is not resolved, the Appellate Body soon will not have enough members to review cases and the vaunted WTO dispute settlement system will grind to a halt.