Judgment of the Court (Fourth Chamber) of 6 October 2021.#TS and Others v Casa Naţională de Asigurări de Sănătate and Casa de Asigurări de Sănătate Constanţa.#Request for a preliminary ruling from the Curtea de Apel Constanţa.#Reference for a preliminary ruling – Social security – Health insurance – Regulation (EC) No 883/2004 – Article 20(1) and (2) – Medical treatment received in a Member State other than the insured person’s Member State of residence – Prior authorisation – Conditions – Requirement for a report by a doctor in the national public health insurance system prescribing a treatment – Recommendation, by way of a second medical opinion, in a Member State other than the insured person’s Member State of residence, of an alternative treatment having the advantage of not creating a disability – Full reimbursement of the medical expenses relating to the alternative treatment – Freedom to provide services – Article 56 TFEU.#Case C-538/19.