The functioning of the European Union (EU) legal system is ensured through an intricate interdependent and non-hierarchical judicial system, where judges at the Court of Justice of the EU (CJEU) must rely on the willing cooperation from other Member States' judges to enforce decisions on EU law matters. Scholars have pointed to the relevance of legal, historical, sociological and political factors in explaining why courts cooperate within the EU judicial system. However, recent scholarly and policy debates underline the relevance of trust-enhancing solutions in addressing some of the current challenges facing the EU legal system: specifically that of judicial defiance of national courts to the authority of the CJEU. These concerns have been aggravated in the context of democratic and rule of law backsliding in Hungary and Poland, which have raised serious doubts about the correct application of EU law within a network of thousands of national courts. Recent theoretical developments claim the existence and development of trust between judges is a functional principle that may encourage cooperation between national and the CJEU. By offering original data collected from surveys, this article offers the first evidence as to what extent trust in the CJEU might enhance cooperation by national courts and, hence, the functioning of the EU legal order.