The Optional Protocol to the Convention on the Elimination of All Forms of Discrimination against Women (OP-CEDAW) is an international treaty which establishes complaint and inquiry mechanisms for the Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW). Parties to the Protocol allow the Committee on the Elimination of Discrimination against Women to hear complaints from individuals or inquire into "grave or systematic violations" of the convention. The Protocol has led to a number of decisions against member states on issues such as domestic violence, parental leave and forced sterilization, as well as an investigation into the systematic killing of women in the Mexican city of Ciudad Juárez, Chihuahua.