The effect of unethical leadership on employees’ unethical pro-organizational behaviour: A meta-analysis [Author Accepted Manuscript]

Background: This meta-analysis examines the relationship between unethical leadership and employees' engagement in unethical pro-organizational behaviours. When leaders lack moral integrity, it can undermine employees' ethical decision-making. By synthesizing evidence across studies, this research aims to clarify the scale and impact of this link, informing interventions to mitigate the harmful effects of unethical leadership on employee behaviour. Methods: A systematic literature search across five online databases identified 129 empirical studies published between 2014 and 2024. These studies investigated the relationship between unethical leadership and unethical pro-organizational behaviours, examining constructs such as exploitative leadership, authoritarian leadership, and abusive supervision. Only studies that were rated as having moderate or strong overall quality based on the QATQS risk of bias assessment were included. The meta-analysis employed a univariate random-effects model, with effect sizes calculated using Fisher's Z coefficient. Results: A total of 20 effect sizes from 12 studies were included, involving 6,892 participants across five countries, four from Asia (i.e., China, Vietnam, Saudi, and Iran) and the United States. The overall effect size was positively significant, indicating that unethical leadership moderately increases employees' unethical pro-organizational behaviours. The substantial heterogeneity suggests variability beyond chance. While the funnel plot and Egger's regression test indicate potential publication bias in the included studies, Duval and Tweedie's trim-and-fill method did not identify sufficient evidence of missing studies to warrant adjusting the effect size. Conclusion: Unethical leadership demonstrates a moderate positive effect on employees' engagement in unethical pro-organizational behaviours. Leaders' unethical conduct directly shapes this trend. However, potential mediating factors, such as a moral engagement, value-congruence, and moderating factors, such as organizational culture and ethical climate, may also influence these associations.