The accession of the European Union to the European Convention on Human Rights is an issue frequently addressed by (not only internationalist) legal scholars, who stress that it would allow for an optimisation of the level of protection of fundamental rights in the European legal area. After reviewing the historical stages of accession, this paper focuses on the second opinion of the Court of Justice regarding it (Opinion 2/13 of 2014). Therein, accession is presented as an unattainable goal, probably because of the refusal of the Court of Justice to submit to the other European court, the Strasbourg Court of Human Rights. Subsequently, the paper reviews the possible effects of accession on the current legal scenario with special attention to the Italian legal system. Finally, it aims at figuring out how accession could affect criminal matters: in particular, by means of an example concerning the principle of legality, the purpose is to demonstrate how accession could lead to an improvement of the criminal guarantees of the European legal area.