摘要:The field of study of the present paper was a doctrinal and case law research whose first scope was the treatment given by the legal system to same-sex marriages nowadays. It draws a legal parallel between Family Law and its comprehensiveness in the social environment, considering the changes in the gregarious groups that form the family entity, as the backdrop and substantiation for the State’s protective evolutions on same-sex unions based on constitutional principles that have motivated litigations before the Supreme Court due to the Legislative Power’s inertia regarding that matter. Thus, this paper analyses the Brazilian Supreme Court’s unanimous decision in a judgment occurred in May 4-5 of the present year that equaled the same-sex marriages to domestic partnerships based on the social claims guided by the constitutional principles of equality, liberty, and dignity of the human being. It finishes by indicating adequate ways to regulate the domestic partnership, whether traditional or homosexual, through contractual effectiveness by examining the legal theories involved.