This text poses the question whether the principles of equal rights of employees performing the same duties and of the non-discrimination in employment should be separately defined after Labour Code was amended by the Act on 16 May 2019. In the author's opinion an affirmative answer should be made. The separation of duties expressed by above-mentioned principles implies the differentiation of sanctions laid down in the case of their violation. The detailed analysis focuses on the construction of invalidity of employment contract provisions and the employer's compensation liability which are the legal consequences of an unequal treatment of employees as established in the Polish Labour Code.

The legality of contractual prohibition or another limitation on the employee's additional employment which goes beyond the scope of competitive activity should be reconsidered in the light of the Act of 9 March 2023 amending the Labour Code and Certain Other Acts (Journal of Laws 2023, item 641), preceded by the Directive (EU) 2019/1152 of the European Parliament and of the Council of 20 June 2019 on transparent and predictable working conditions in the European Union (OJ L 186, p. 105). The wording of newly introduced Article 261 of Labour Code does not lead to unambigous conclusions. Hence, in order to determine the consequences of above amendment the other metods of interpretation of the law must be used. In the light of that interpretation the Polish legislator has excluded the competence of labour relationship parties to conclude a contract which sets out a prohibition of additional employment. In the author's opinion such a regulation is an excessive means of limiting the freedom to shape the content of that legal relationship.