Gender-based violence is recognized as a type of discrimination in international human rights law. However, the European Court of Human Rights (ECtHR)did not establish a connection between the prohibition of discrimination in securing rights under the European Convention on Human Rights and gender-based violence until 2009. This approach changed with the court’s landmark Opuz decision. In Opuz, the court adopted a feminist interpretation of the due diligence standard. This interpretation fundamentally challenged the traditional understanding of state responsibility for human rights violations in the ‘private sphere.’ Accordingly, member states are now responsible not only for their own actions but also for their lack of due diligence in their failures to prevent or respond to gender-based violence and take reasonable steps to prevent it. Although the ECtHR still fails to acknowledge gender-based violence as a type of discrimination in some cases, this chapter suggests that the Opuz decision constitutes a milestone.