Ban on torture, cruel, inhuman or degrading treatment

The Ban on torture, cruel, inhuman or degrading treatment is enshrined in
Article 5 of the Universal Declaration of Human Rights.

In cases of violations of this human right (explained here),

All persons may turn to the these organs/institutions:

Human Rights Committee (if the optional protocol is ratified by the state)

Committee against Torture (if competence is accepted by the state)

Special Rapporteur on torture and other cruel, inhuman or degrading treatment or punishment

In case of serious crimes such as genocide or war crimes one may turn to:

International Criminal Court 

Migrants may turn to:

Special Rapporteur on the human rights of migrants

Indigenous people may turn to:

Special Rapporteur on the situation of human rights and fundamental freedoms of indigenous people

Persons being in an African country may turn to:

African Commission or Court on Human Rights and Peoples’ Rights

In the case of a deprivation of liberty not recognized by the State, one may turn to:

Committee on Enforced Disappearances

Working Group on Enforced or Involuntary Disappearances