A/HRC/42/33 Yemen, the Commission noted that it has been a challenge for it to corroborate some information. 14. Given the highly volatile environment, victims and witnesses who cooperate with the National Commission are particularly exposed, including to reprisals by parties to the conflict. The Commission must be guided by the “do no harm” principle and, in accordance with relevant international practice, an effective mechanism to protect victims and witnesses who come into contact with it must be put in place. 15. Under treaty and customary international law, States have the primary responsibility to investigate and prosecute gross violations of international human rights law and serious violations of international humanitarian law and to provide effective remedies to victims, including reparations. Under the presidential decrees that established the National Commission, it has the responsibility to investigate allegations of violations and abuses committed by all parties in Yemen and to submit its reports and cases to the AttorneyGeneral to complete investigations and prosecution. However, while the Commission has submitted investigation files to the public prosecution and the judiciary, OHCHR has not been informed about any initiated or completed court cases following such submissions. 16. The deployment of field monitors in 20 governorates is key to increase the accessibility of the National Commission, but further efforts are required in that regard and to improve its outreach. For instance, the establishment of sub-offices in suburban areas would further facilitate access to the Commission and reporting of cases. While the conflict and its negative impact on infrastructure limits resort to the media, such as local radio broadcasting, it would be important for the Commission to develop a communication strategy to enhance its visibility throughout Yemen and disseminate information about its mandate and role. The Commission could also expand information contained on its website, Facebook page and Twitter account. OHCHR notes that in its sixth report, the Commission reported that it had engaged with civil society actors and had received from them factual information about human rights violations that assisted it in discharging its mandate effectively. It is important that the Commission pursue its engagement with civil society actors to enhance its outreach. III. Technical assistance provided by the Office of the United Nations High Commissioner for Human Rights 17. Pursuant to Human Rights Council resolutions 36/31, 39/16 and 39/21, OHCHR has continued to provide technical assistance and capacity-building to the National Commission. In consultation with OHCHR, the Commission identified priority areas for the technical assistance it requires. OHCHR conducted various training activities for the members and staff of the Commission in Ethiopia, Jordan, Lebanon, Malaysia, Qatar, Switzerland and Yemen, which are described in this section of the report. 18. In accordance with its usual methodology, in performing the mandate assigned by the Human Rights Council in its resolution 39/21 OHCHR has been guided by the principles of independence, impartiality, objectivity, credibility and professionalism. To assess the needs of the National Commission and develop customized capacity-building activities, in 2016 OHCHR sent questionnaires and surveys to the commissioners, staff members of the Secretariat and field monitors. OHCHR also held regular collaborative and performance consultations with the Chair and members of the Commission to define the purpose of capacity-building activities. OHCHR used training methodologies, publications and techniques it has developed, such as Integrating a Gender Perspective into Human Rights Investigations: Guidance and Practice; Who’s Responsible? Attributing Individual Responsibility for Violations of International Human Rights and Humanitarian Law in United Nations Commissions of Inquiry, Fact-Finding Missions and other Investigations; and A Practitioner’s Toolkit on Women’s Access to Justice Programming. 19. Moreover, adherence to the standards of objectivity, transparency, impartiality and professionalism has been at the core of the capacity-building provided by OHCHR to strengthen the National Commission, its functioning and credibility. Presidential Decree No. 50 of 2017 indeed provides that the methodology of the Commission is based on the 4