subsequent practice of States; in other words, to determine the context of a particular treaty. In addition, for the purposes of interpretation, Article 31(3) of the Vienna Convention authorizes the use of means such as agreements or practice 388 or relevant rules of international law 389 that States have mentioned in relation to the treaty, which is related to an evolutive view of the interpretation of the treaty. 246. In the instant case, the evolutive interpretation is particularly relevant, bearing in mind that IVF is a procedure that did not exist when the authors of the Convention adopted the content of Article 4(1) of the Convention (supra para. 179). Therefore, the Court will analyze two issues in the context of the evolutive interpretation: (i) the pertinent developments in international and comparative law concerning the specific legal status of the embryo, and (ii) the regulations and practice of comparative law in relation to IVF. C.3.a) The legal status of the embryo 247. It has been noted that, in the Case of Vo. v. France, the European Court of Human Rights indicated that the potentiality of the embryo and its capacity to become a person requires a protection in the name of human dignity, without making it a “person” with the “right to life” (supra para. 237). 248. For its part, article 18 of the Oviedo Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine (hereinafter “the Oviedo Convention”), adopted within the framework of the European Union, 390 establishes the following: Article 18. Research on embryos in vitro: 1. Where the law allows research on embryos in vitro, it shall ensure adequate protection of the embryo. 2. The creation of human embryos for research purposes is prohibited. 249. Consequently, this treaty does not prohibit IVF, but rather the creation of embryos for research purposes. Regarding the status of the embryo in this Convention, the ECHR has indicated that: The Oviedo Convention on Human Rights and Biomedicine […] is careful not to give a definition of the term “everyone”, and its explanatory report indicates that, in the absence of unanimous agreement on the definition, the member States decided to allow domestic law to provide clarification for the purposes of the application of that Convention […] The same is true of the Additional Protocol on the region to determine which of them permitted either paid or unpaid political advertising and in which countries such publicity was free. Likewise, in the case of Hirst v. United Kingdom, the Court took into account the “Law and practice in the Contracting States” in order to determine which countries suspended the right to vote of a person convicted of a crime, for which purpose it surveyed the legislation of 48 European countries. 388 Cf. ECHR, Case of Rasmussen v. Denmark (No. 8777/79), Judgment of 28 November 1984, para. 41; Case of Inze v. Austria, (No. 8695/79) Judgment of 28 October 1987, para. 42, and Case of Toth v. Austria, (No. 11894/85), Judgment of 25 November 1991, para. 77. 389 390 Cf. ECHR, Case of Golder v. United Kingdom, (No. 4451/70), Judgment of 12 December 1975, para. 35. The Oviedo Convention establishes that States Parties “shall protect the dignity and identity of all human beings and guarantee everyone, without discrimination, respect for their integrity and other rights and fundamental freedoms with regard to the application of biology and medicine” and adds that “[e]ach Party shall take in its internal law the necessary measures to give effect to the provisions of this Convention.” The Oviedo Convention was adopted on April 4, 1997, in Oviedo, Asturias, and entered into force on December 1, 1999. It was ratified by 29 Member States of the Council of Europe, with six reservations.