94. Given that the American Convention does not have an explicit definition of discrimination, the Court has taken into account various instruments of international law to define it as “any distinction, exclusion, restriction, or preference based on certain grounds, such as race, color, sex, language, religion, political or other opinion, national or social origin, property, birth, or any other social condition, and whose object or result is to nullify or impair recognition, enjoyment, or exercise, under conditions of equality, of human rights and fundamental freedoms of all people”48. Likewise, it should be noted that there is no exhaustive list of prohibited categories of discrimination, but rather that the expression "any other social condition" in Article 1.1 of the American Convention must be interpreted from the perspective of the option most favorable to the person and of the evolution of fundamental rights in contemporary international law49. 95. As the IACHR has pointed out, the development of the right to equality and non-discrimination makes it possible to identify various definitions of it. For example, one concept is related to the prohibition of arbitrary difference of treatment -understanding by difference of treatment distinction, exclusion, restriction, or preference; another is related to the obligation to create conditions of real equality vis-à-vis groups that have historically been excluded and are at greater risk of being discriminated against. Likewise, and linked to these two definitions, there is that of indirect discrimination or disproportionate impact of norms, actions, or policies that seem neutral but that have differentiated effects in certain group50. Likewise, the Inter-American Court has indicated on indirect discrimination that “international human rights law not only prohibits deliberately discriminatory policies and practices, but also those whose impact is discriminatory against certain categories of people, even when the intention cannot be proven discriminatory”51. 96. The principle of equality in the American Convention has two important references in Articles 1.1. and 24 of the Convention. On the one hand, Article 1.1 of the Convention is a general norm whose content extends to all the provisions of the treaty and establishes the obligation of the States Parties to respect and guarantee the full and free exercise of the rights and freedoms recognized therein. "without any discrimination." That is, whatever the origin or the form it assumes, any treatment that may be considered discriminatory with respect to the exercise of any of the rights guaranteed in the Convention is, per se, incompatible with it”52. On the other hand, article 24 provides the right to equal protection, and is applicable in the event that discrimination refers to unequal protection of the domestic law or its application53. - The duty of prevention in the context of the fight against terrorism 97. According to the Inter-American Convention against Terrorism, acts of terrorism constitute “a serious criminal phenomenon that deeply worries all member states, threatens democracy, impedes the enjoyment of human rights and fundamental freedoms, threatens the security of the States, destabilizing and undermining the foundations of the entire society, and seriously affects the economic and social development of the States of the region”54. In view of the seriousness of such acts, in international law there are several instruments aimed at the prevention, suppression, and eradication of the different forms of terrorist violence. I/A Court H.R., Gender identity, and equality and non-discrimination with regard to same-sex couples. State obligations in relation to change of name, gender identity, and rights deriving from a relationship between same-sex couples (interpretation and scope of Articles 1(1), 3, 7, 11(2), 13, 17, 18 and 24, in relation to Article 1, of the American Convention on Human Rights). Advisory Opinion OC-24/17 of November 24, 2017. Series A No. 24, para. 62. 49 IACHR. Report No. 112/12. Case 12.828. Merit. Marcel Granier and others. Venezuela. November 9, 2012, para. 160; and IACHR. Report No. 75/15. Case 12.923. Merit. Rocío San Miguel Sosa and others. Venezuela. October 28, 2015, para. 171. IACHR. Report on Poverty and Human Rights in the Americas. OEA / Ser.L / V / II.164 Doc. 147. September 7, 2017, para. 153. 50 IACHR, Merits Report No. 85/10. Case 12.361. Gretel Artavia Murillo and others (In vitro fertilization). Costa Rica, para. 125. 51 I/A Court H.R., Case of Nadege Dorzema et al. v. Dominican Republic. Merits, Reparations and Costs. Judgment of October 24, 2012. Series C No. 251, para. 234; I/A Court H.R., Case of expelled Dominicans and Haitians v. Dominican Republic. Preliminary Objections, Merits, Reparations and Costs. Judgment of August 28, 2014. Series C No. 282, para. 263. 52 I/A Court H.R., Gender identity, and equality and non-discrimination with regard to same-sex couples. State obligations in relation to change of name, gender identity, and rights deriving from a relationship between same-sex couples (interpretation and scope of Articles 1(1), 3, 7, 11(2), 13, 17, 18 and 24, in relation to Article 1, of the American Convention on Human Rights). Advisory Opinion OC-24/17 of November 24, 2017. Series A No. 24, para. 63. 53 I/A Court H.R., Case of expelled Dominicans and Haitians v. Dominican Republic. Preliminary Objections, Merits, Reparations and Costs. Judgment of August 28, 2014. Series C No. 282, para. 262. 54 General Assembly of the OAS, Inter-American Convention against Terrorism, June 3, 2002. 48 18