In 2005, Law No. 13 amended the Spanish Civil Code to allow for same-sex marriage. More than 50 Deputies of the Popular Party brought a claim before the Tribunal Constitutonal, which alleged the violation of, inter alia, Article 32 of the Spanish Constitution. According to this provision, men and women have the right to marry. The Tribunal Constitucional (http://hj.tribunalconstitucional.es/HJ/es/Resolucion/Show/23106)followed an evolutionary interpretation of the Constitution, holding that its Article 32 did not prevent the legislator from passing a law such as the one in question. The Court indicated that the recognition of same sex marriage was a legislative option supported by the principle of equality; nevertheless, it failed to ground its decision upon the right to non-discrimination on the basis of sexual orientation.
In order to support its finding, the Tribunal Constitucional made use of comparative law, by making reference to the legislation and court decisions in other countries. The Tribunal initially referred to a Privy Council precedent solely to borrow the image of the Constitution as a “growing tree” (Edwards v A.G. Canada  AC 123, 1 DLR 98 (PC), but it then mentioned the use of this analogy in the Canadian Supreme Court’s judgment on same-sex marriage (Reference re Same-Sex Marriage,  3 S.C.R. 698, 2004 SCC 79). In so doing, the Tribunal displayed a clear comparative effort aimed to support the assessment of the legal point it was seized of. Similarly, the Tribunal introduced a full overview of the jurisdictions recognizing same-sex marriage, either under their laws or subsequent to a judicial decision (see the reference to the Massachusetts Supreme Court - Goodridge v. Department of Public Health, 798 N.E.2d 941 (Mass. 2003)-, and the Constitutional Court of Slovenia - Judgment of 2 July 2009, Blaži? and Kern v. Slovenia U-I-425/06-10-).
Also, the Tribunal Constitucional opted for a consistent interpretation of Article 32 of the Constitution in light of the ECtHR’s case-law. In Schalk and Kopf v. Austria, the Strasbourg Court had issued an evolutionary interpretation of Article 12 ECHR, drawing support from the literal tone of Article 9 of the EU Charter of Fundamental Rights, which does not explicitly refer to men and women.