The article aims to provide a critical analysis of the regulation of Article 138 MC, which stipulates service provider’s liability for refusal to provide a service that he or she is obliged to provide. The reasoning presented aims to determine actual scope of penalisation by indicating that liability under Article 138 MC can be considered only when a service provider is obliged to provide a service within the meaning of civil law. The obligation may result from the law but, as a rule, a contract between a service provider and a customer is its source. In general, a service provider cannot free himself/herself from the obligation to provide a service only based on religious rules or conscience (called conscientious objection). If he or she states that the provision of the service is against the rules of his/her religion or conscience, he or she can refrain from entering a contract. The article presents a few special types of contracts and indicates the way in which conscience is protected in each case (Article 53 of the Constitution of the Republic of Poland). The article also discusses doubts raised in connection with constitutionality of Article 138 MC and indicates, inter alia thanks to a comparison with other norms of the Misdemeanour Code, that the provision is not disproportional and does not violate the constitutional principle of economic freedom. Therefore, its potential change or repealing should be considered in the context of shaping criminal law policy through legislation and not questioning its compliance with the basic law. Working on the article, the author used in particular a formal-dogmatic method as well as a legal-comparative method.