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 [1930] 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,   [2004] 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.

The Tribunal repeated this exercise as regards the rationale of Law 13/2005. It identified the purpose of the law in the “equation between the legal status of homosexual and heterosexual persons,” and evoked several ECtHR’s decision, as well as Art. 21 of the EU Charter of Fundamental Rights as evidence that this purpose is underpinning a general trend. The case-law of the Strasbourg Court was also heavily cited (starting with the leading case of 2002 Fretté v. France, App. no. 36515/97) to prove that States enjoy a wide margin of discretion in regulating the possibility to extend the institution of marriage to same-sex couples.

A. The case is a prime example of the use of comparative method to   strengthen judicial reasoning in fundamental rights adjudication.   Interestingly, the Tribunal Constitucional did not simply mention   supranational and foreign authorities ad   abundantiam, but as decisive evidence strengthening its conviction that   the institution of marriage as a union between a man and a woman is fading   out. In this connection, it is worth paying attention to the context of the   judgment, which differentiates it from other cases on same-sex marriages delivered   by courts of other States. The Tribunal   handed down in response to a challenge to provisions establishing advanced   same-sex rights, and not in response to challenges to the lack of similar provisions, or invocations of equal treatment   by members of a discriminated group. The claimants built had built their case   on the assumption that equal treatment ensured by Law 5/2013 did not serve   the purpose of equality, as the Law equated two situations that are so   different that fairness would rather require a different treatment. Being   this a matter of purely constitutional nature, the Tribunal is keen to draw from external sources and engage in   comparative analysis to bring ammunition to its opinion. The intensive use of   normative and judicial examples from other jurisdictions is geared towards   the demonstration that a global trend is in action, and that therefore the   constitutional soundness of the law impugned is out of question

B.  The relative weight of the references to EU law and the ECtHR is higher than that of the list of national statutes and decisions supporting same-sex marriage. The reference to Art. 21 of the EU Charter of Fundamental Rights and the continuous reliance on the ECtHR’s judgments on the right to family life and non-discrimination are clearly premised on a sense of deference. Since Spain shares the constitutional instruments on fundamental rights that belong to the EU and ECHR systems, it cannot ignore their content and the case law that stems therefrom, and possibly it is called to respect them, at least through the duty of consistent interpretation codified in Art. 10(2) of the Constitution. Interestingly, the Tribunal cites the Schalk v. Kopf case, that several other national courts put forward as example of the absence of an obligation to recognize same-sex marriages. The Tribunal, instead, highlights the passages where the Strasbourg Court acknowledges that marriage is not necessarily a heterosexual union. Together with Fretté and the other similar cases, this judgment serves the purpose of validating the ECHR-compliance of Law 13/2005, and crowns the Tribunal’s effort to frame it as a normal expression of evolutionary constitutionalism, rather than an unconstitutional extravagance.