The purpose of this study is to provide a theoretical and doctrinal analysis of two variants of established practice as instruments for strengthening legal certainty in labour law. The analysis is comparative in nature and aims to identify both similarities and differences between these variants, as well as to demonstrate their potential for supporting the protective function of labour law. First, the paper examines custom and customary law within the workplace communi­ty. It then analyses labour-law interpretation “binding” by consensus as an analogous, though differently structured, mechanism of stabilization. Although the latter phenome­non occurs across various branches of law, its examination in the context of labour law appears particularly valuable in light of the specific features of this field and the special role that legal certainty plays for the parties to the employ­ment relationship. The autonomy of legal dogmatics entails that the modes of argumentation and justification under­lying the “binding force” of interpretation differ depend­ing on the branch of law concerned. Intuitions regarding the “binding” nature of interpretation arise differently in criminal or tax law than they do in labour or civil law. The analysis undertaken in this study may therefore serve as a useful point of departure for more detailed inquiries into the requirements of legal certainty for the parties to the em­ployment relationship.

The purpose of the paper is to address ongoing disputes regarding the interpretation of labor law. The authors aim to explore whether the method of enacting normative acts affects the interpreter’s goals during the interpretation process. Some literature suggests that when they are en­acted through agreement (such as labor collective agree­ments), in contrast to acts not enacted in this manner, the interpreter should prioritize the actual intentions of the parties involved over the literal meaning of their provi­sions. The authors argue that there is no difference in this regard among various normative acts. In all cases, the au­thor’s intention is what interpreters seek.

The paper focuses on a problem of compliance legal norm — that is so called privileging the employee's principle (in scope that is currently predicted in an Article 9 para. 2 of Polish Labour Code) with the Constitution of Republic of Poland. The purpose of paper is justification of thesis that subjected principle is de lege lata constitutional norm and showing important consequences of this conclusion. In order to accomplishment of this purpose, article shows results of analysis of relevant regulations that were binding in different moments of time, and use theoretical concepts, especially such as the integrated concept of legal principles and the typological linguistic content of the predicate.