labour law has for the labour market or for the society as a whole. This would be an extremely ambitious and complex approach. And it only could be fruitfully started in an interdisciplinaryeffort, it would go far beyond the competence of legal experts. And even then it would be doubtful whether reliable results could be identified. Therefore, this paper does not attempt to contribute to this debate at all. The perspective here is much more modest. Effectiveness in the sense used in this paper exclusively refers to the question whether and in how far the normative framework of labour law is implemented in actual reality. The focus is on gaps between the law in the books and the law in action. In this context it is of utmost importance to identify the mechanisms which promote or prevent such effectiveness. Effectiveness of law as understood here in the meantime has become a well established branch of research in sociology of law. Even if the goal is modestly framed it has to be stressed that also in this limited perspective it is difficult to provide a precise analysis. Scholarly researched empirical data are rather the exception than the rule. Therefore, there is no alternative but to build at least to a certain extent on speculations, based of course on close familiarity with the functioning of the system.