Human rights defenders provide an invaluable source of information to international bodies on emerging human rights problems, and collaboration between civil society and the UN and regional human rights mechanisms is vital to their work. The UN, the ACHPR and the IACHR all have normative agreements and rules of procedure explicitly prohibiting acts of reprisals by States and non-State actors. Defenders nevertheless continue to face great risks when trying to engage with the United Nations, its mechanisms and representatives in the field of human rights, and/or the regional human rights system. Reprisals or the threat of reprisals can take very sophisticated forms and States are becoming increasingly aware of the ability of reprisals to prevent human rights defenders from speaking out. It is crucial that acts of reprisals are promptly investigated, perpetrators brought to justice, and victims be provided an effective remedy. Such steps towards the fight against impunity and towards full accountability for reprisals may further constitute an important preventive measure and should be combined with other measures facilitating civil society's safe and unimpeded access to the UN and the regional human rights institutions.