Judicial administration of justice through reasoned interpretation, application and clarification of legal principles and rules is among the oldest paradigms of 'constitutional justice'. The principles of procedural justice underlying WTO dispute settlement procedures, like the conformity of WTO dispute settlement rulings with principles of 'substantive justice', remain controversial. This contribution criticizes the recent, harsh condemnation of the WTO dispute settlement rulings in the Brazil Tyres case as 'committing grave injustice'. After recalling the customary law requirement of interpreting treaties and settling international disputes 'in conformity with principles of justice' and human rights, the contribution examines the WTO Appellate Body case-law from the perspective of diverse conceptions of 'conservative' and 'reformative justice', 'general' and 'particular justice', procedural and substantive justice, national and multilevel 'constitutional justice', and judicial protection of transnational rule-of-law for the benefit of citizens. The article concludes that the panel, appellate and arbitration reports in the Brazil Tyres dispute, like many other WTO Appellate Body reports, reflect a growing concern 'to administer justice' in WTO dispute settlement proceedings. WTO judges and investor-state arbitrators should follow the example of the ICJ and of European courts and clarify the 'principles of justice' justifying their settlement of international economic disputes so that 'justice is not only done, but also seen to be done', albeit subject to 'trial and error'. Legal practitioners should support – and, as part of the 'invisible college of international lawyers', hold accountable – the emergence of an 'international judiciary' as an 'epistemic community' committed to defending rule of law, peaceful settlement of disputes and 'principles of justice' in mutually beneficial economic cooperation among citizens across national frontiers.