Where the executing judicial authority has objective, reliable, specific and properly updated information showing systemic or generalised deficiencies in detention conditions in the issuing Member State, it must assess whether there are substantial grounds for believing that the requested person would face a real risk of inhuman or degrading treatment under Article 4 of the Charter in the prison where it is actually intended that person be detained. That assessment must cover all relevant physical aspects of those conditions, including personal space in the cell, sanitary conditions and the extent of the detainee’s freedom of movement within the prison. That assessment is not limited to obvious inadequacies. For that assessment, the executing judicial authority must request the information it considers necessary from the issuing judicial authority and must, in principle, rely on that authority’s assurances, unless there are specific indications that the detention conditions infringe Article 4 of the Charter. As regards personal space, and in the absence of EU minimum standards, the executing judicial authority must use the minimum requirements under Article 3 ECHR as interpreted by the European Court of Human Rights. In calculating that space, the area occupied by sanitary facilities must be excluded and the space occupied by furniture must be included. Detainees must still be able to move around normally within the cell. The executing judicial authority cannot rule out a real risk merely because the person has a legal remedy in the issuing Member State to challenge detention conditions or because that State has legislative or structural measures to strengthen monitoring of detention conditions. If that authority finds substantial grounds for believing that the requested person would face such a risk in the prison where it is actually intended that person be detained, it cannot balance that finding against the efficacy of judicial cooperation in criminal matters or the principles of mutual trust and recognition when deciding on surrender.