This request for a preliminary ruling concerns the interpretation of Articles 3(2) and 17(1) of Regulation (EU) No 604/2013 of the European Parliament and of the Council of 26 June 2013 establishing the criteria and mechanisms for determining the Member State responsible for examining an application for international protection lodged in one of the Member States by a third-country national or a stateless person (OJ 2013 L 180, p. 31) (‘the Dublin III Regulation’), Article 267 TFEU and Article 4 of the Charter of Fundamental Rights of the European Union (‘the Charter’). This request has been made in proceedings between, on the one hand, C. K., H. F. and their child A. S. and, on the other hand, the Republika Slovenija (Republic of Slovenia), represented by its Ministry of the Interior, concerning the transfer of those persons to Croatia, designated as the Member State responsible for examining their application for international protection in accordance with the provisions of the Dublin III Regulation. The Court (Fifth Chamber) ruled that: 1. Article 17(1) of Regulation (EU) No 604/2013 of the European Parliament and of the Council of 26 June 2013 establishing the criteria and mechanisms for determining the Member State responsible for examining an application for international protection lodged in one of the Member States by a third-country national or a stateless person must be interpreted as meaning that the question of the application, by a Member State, of the ‘discretionary clause’ laid down in that provision is not governed solely by national law and by the interpretation given to it by the constitutional court of that Member State, but is a question concerning the interpretation of EU law, within the meaning of Article 267 TFEU. 2.  Article 4 of the Charter of Fundamental Rights of the European Union must be interpreted as meaning that: –        even where there are no substantial grounds for believing that there are systemic flaws in the Member State responsible for examining the application for asylum, the transfer of an asylum seeker within the framework of Regulation No 604/2013 can take place only in conditions which exclude the possibility that that transfer might result in a real and proven risk of the person concerned suffering inhuman or degrading treatment, within the meaning of that article; –        in circumstances in which the transfer of an asylum seeker with a particularly serious mental or physical illness would result in a real and proven risk of a significant and permanent deterioration in the state of health of the person concerned, that transfer would constitute inhuman and degrading treatment, within the meaning of that article; –        it is for the authorities of the Member State having to carry out the transfer and, if necessary, its courts to eliminate any serious doubts concerning the impact of the transfer on the state of health of the person concerned by taking the necessary precautions to ensure that the transfer takes place in conditions enabling appropriate and sufficient protection of that person’s state of health. If, taking into account the particular seriousness of the illness of the asylum seeker concerned, the taking of those precautions is not sufficient to ensure that his transfer does not result in a real risk of a significant and permanent worsening of his state of health, it is for the authorities of the Member States concerned to suspend the execution of the transfer of the person concerned for such time as his condition renders him unfit for such a transfer; and –        where necessary, if it is noted that the state of health of the asylum seeker concerned is not expected to improve in the short term, or that the suspension of the procedure for a long period would risk worsening the condition of the person concerned, the requesting Member State may choose to conduct its own examination of that person’s application by making use of the ‘discretionary clause’ laid down in Article 17(1) of Regulation No 604/2013. 3. Article 17(1) of Regulation No 604/2013, read in the light of Article 4 of the Charter of Fundamental Rights of the European Union, cannot be interpreted as requiring, in circumstances such as those at issue in the main proceedings, that Member State to apply that clause.