The paper briefly reviews the most important economic models from which arguments can be drawn in support of (or against) the coherence between labour law aims and effects, particularly focusing on the principal/agent model, which considers the work contract as partially functioning as a sort of insurance policy aimed to guarantee a certain degree of equality among workers notwithstanding their different ability and luck. The paper then assumes the traditional labour law commitment to building equality among workers as a test-bench of the labour law effectiveness. It then proposes a crucial test for the equalization principle’s practical functioning: when is it fair to dismiss an inefficient worker? The paper analyses the current mechanism of judicial application of just cause for dismissal, showing how, in its Italian version, it actually causes the most rigid courts’ orientation – instead of the average one, or the median one – to be assumed by employers and employees as a benchmark for their behaviour in case of litigation.