The central objective of this article is to analyze the International Responsibility of the Brazilian State in the case of violence against women, in particular, to the case that became emblematic in Brazil and outside it, which was the involvement of violence against Maria da Penha Maia Fernandes practiced by, today, her ex-husband. Here the reference is the case 12,051 (Maria da Penha Maia Fernandes v. Brazil), which was opened on August 20, 1998 by the Inter-American Commission on Human Rights of the Organization of American States (OAS). From the intersection between domestic violence committed against Maria da Penha Maia Fernandes and the Institute of International Responsibility, it was verified how the application of an international institute, through the Inter-American Commission on Human Rights of the Organization of American States (IACHR-OAS) influenced the creation of legislation that ensures women’s rights in the Brazilian State.