Purpose--The purpose of this study is to examine the relationship between interactional justice, as a type of organizational justice that reflects the teachers' perceived fairness of supervisor treatment, and their non-task behavior in terms of organizational citizenship behavior (OCB) and deviant workplace behavior (DWB). Design/methodology/approach--Data were collected from 270 teachers (by e-mail) and 22,599 students (by personal distribution) at a Spanish public university. Structural Equation Modeling (SEM) was used for testing mediation and multiple regression for analyzing the non-task and teaching satisfaction association. Findings--Results show that justice is an antecedent of group commitment that fully mediates the relationship between justice and non-task behavior except DWB-Colleagues. Results also reveal an association between non-task behavior, except DWB-Organization and DWB-Colleagues, and teaching satisfaction. Research limitations/implication--The researched teachers' job conditions are inherent to the peculiarities of the public sector that may limit the ability to extrapolate the findings in the private sector. The findings provide a more understandable mechanism of the influence of the supervisor's justice on non-task behavior and, in turn, on teaching satisfaction. Practical implications--These findings contribute to a better understanding of the ways in which universities can control non-task behavior and provide lines to design a more efficient department management strategy. The emotional and fair proximity of the supervisor, eliciting the group teachers' sense of affective commitment, appears as an effective quality strategy for universities. Originality/value--The study of the joint interaction of justice and group commitment variables against DWB and in favor of OCB, and its consequent effect on teaching quality, is unprecedented in higher education. (Contains 3 figures and 6 tables.)