This book analyses two dimensions of judicial decision-making at the World Trade Organisation (WTO): the substantive outcome produced and the judicial style embraced, in cases concerning national measures taken for non-trade objectives. Drawing on legal theory, empirical studies of judicial decision-making and an analysis of all the major non-trade cases of the WTO, the book concludes that the dispute settlement decisions can be understood in light of the fact that the WTO dispute settlement bodies, like other courts, need to legitimise their decisions. Both the substance and style of WTO judicial decision-making contribute in this regard. On the substantive side, there is a relatively mixed outcome of cases, in terms of the interpretations chosen. The WTO Appellate Body’s interpretations neither consistently favour trade interests nor do they systematically enhance the regulatory space of WTO Members. The dispute settlement bodies also have a distinct judicial style that relies on discursive (rather than institutional) sources of authority and is predominantly formalist.