By using a longitudinal bi-annual dataset (2012–2018) from the European Commission for the Efficiency of Justice (Cepej) for 22 EU countries, this study tests four hypotheses that have been derived from rational choice theory at individual and aggregated level. The positive associations between caseload and productivity support the hypothesis that judges sacrifice leisure or the quality of their decisions to achieve a reduction in backlogs. While the lack of association between the number of assistants and judge’s productivity supports the hypothesis that appointing new staff reduces caseload, thereby inducing judges to substitute time they spend on resolving cases for leisure or improving the quality of their decisions, while the positive association between the number of judges and productivity contradicts this hypothesis. The finding that assistant’s caseload negatively moderates the relationship between judge’s caseload and judge’s productivity supports the hypothesis that as the caseload of assistants increases, judges are releaved of more administrative tasks, thereby allowing judges to spend more time on leisure or improving the quality of their decisions rather than on resolving cases. Our findings suggest that assistants use similar trade-offs as judges and affect judges’ utility maximizing behaviour.