Recently, in a very high-profile decision, the US Court of Appeals for the DC Circuit in Republic of Argentina v BG Group PLC1 annulled a $185 million arbitration award on the basis of its independent review of the arbitrators’ decision on the arbitrability of the dispute. Once again, this case has brought the question of ‘who decides arbitrability’ to the forefront in the United States. BG Group not only raises questions about the proper allocation of authority between judge and arbitrator, it also underscores the implications of judicial overreaching on the success of international arbitration, particularly in the enforcement context. Not surprisingly, BG Group has generated much concern over the role of courts in arbitration in the United States and, for some, has called into question the principle of finality on which parties seeking to enforce non-domestic arbitral awards in the United States rely.