This study investigates the constitutional protection of LGBTI rights in South America and Mexico. Under the theoretical framework of Nancy Fraser’s postwestphalian democratic justice, it questions whether the constitutional protection of these rights in such countries is satisfactory in order to move forward towards the accomplishment of justice to LGBTI persons. The research conducts an empirical study and undertakes a qualitative analysis using the techniques of literature review, documental analysis, and survey. Among the results, it was determined that only two of the analysed constitutions expressly prohibits both sexual orientation – and gender identity-based discrimination. Only one of them uses gender-neutral language in the provision regarding civil union and, therefore, enables the union between two people of the same gender. Under another perspective, the answers of the majority of the Latin-American organizations in the survey indicated that the constitutional protection of LGBTI rights is unsatisfactory in their countries. Therefore, after the analysis of all the data obtained in the research, it was possible to conclude that the constitutional protection is precarious and does not guarantee the most basic rights to LGBTI population.