According to the provision of Article 229 § 4 of the Labour Code, in case of a medical certificate of contraindication to work in a certain position, the employer is legally prohibited from allowing the employee to work. This is not the only legal consequence of a negative medical certificate, which may in fact become the cause of further measures concerning the content and durability of the contractual employment relationship. A certificate stating the existence of medical contraindications to work may also constitute a sufficient basis for the employer to terminate the employment relationship. On the other hand, psycho-physical incapacity to work may deprive the employee of the right to remuneration. Finally, a negative medical certificate may also justify the employer's interference in the content of the employment relationship with regard to the nature and extent of the work assigned. The purpose of this study is to identify, systematise and characterise the legal consequences of a negative medical certificate in the field of content and durability of the contractual employment relationship.

The article presents a multi-threaded analysis of the principle of promoting the work-life balance for parents and carers, which enjoys a relatively strong normative foundation in national, international and European legal instruments. First, the complex nature of the concept of work-life balance is outlined. The hypothesis according to which – from the theoretical and legal point of view – the concept of supporting the balance between work and private life can be perceived as a principle of labour law, is discussed further. Then, the influence of European law on the development of WLB programs in the field of labour law is demonstrated. In this section, particular attention is paid to Directive 2019/1158. In the last part of the analysis, the previous observations and conclusions are linked and compared with the current realities of the Polish labour market and the evolving legal system.