The ruling of the European Court of Human Rights (ECHR) on Thursday, which supports the possibility that the Constitutional Court may veto, in certain cases, the processing of motions in favour of the right to self-determination or against the monarchy, has been a bucket of cold water, and there will be time to analyse it. In this article I focus on another issue relating to the ECHR. In the framework of the negotiations between Junts per Catalunya and Pedro Sánchez's executive in Switzerland, on Monday it became known that the Spanish Council of Ministers would approve Spain's accession to Protocol 16 of the European Convention on Human Rights (ECHR; Treaty No. 214) immediately. This protocol, which entered into force in August 2018, introduced a significant innovation in the judicial system for the protection of human rights in Europe. Specifically, it allows the highest instances of state courts designated by the Member States to request an advisory opinion from the European Court of Human Rights (ECHR) on questions of principle related to the interpretation or application of the rights and freedoms defined in the Convention. Applications can be made in the context of cases pending before the competent domestic courts, and the ECtHR has the power to accept the application and issue an opinion which is formally non-binding. Although the innovation is significant, it is not comparable with the impact of the preliminary ruling procedure in European Union (EU) law due to the different legal structure of the Protocol No. 16 procedure compared to the preliminary ruling procedure at the Court of Justice of the EU (CJEU) – the so-called preliminary question, which is binding because the aim is to ensure the supremacy of EU law.