The Universal Declaration of Human Rights, 1948, provides thatall human beings are born free and equal in dignity and rights. The principle of jus cogens stems from this.
Article 53 of Vienna Convention on the Law of Treaties, 1969 explains that peremptory norms are accepted and recognized under international law and that there should be no derogation of these rights.
In the case of The Prosecutor v Anto Furundzija, the judge explained jus cogens to be;
“ ..that is, a norm that enjoys a higher rank in the international hierarchy than treaty law and even ‘ordinary’ customary rules. The most conspicuous consequence of this higher rank is that the principle at issue cannot be derogated from by States through international treaties or local or special customs or even general customary rules not endowed with the same normative force”.
These norms include but are not limited to the crimes of torture and aggression, the prohibition of genocide, the prohibition of crimes against humanity, and the basic rules of international humanitarian law. 
The Rome Statute of the International Criminal Court stipulates what constitutes crimes against humanity, including murder, extermination, enslavement, imprisonment or severe deprivation of physical liberty, torture and other inhumane acts of similar character that intentionally cause great suffering or serious injury physically and mentally.
Erga omnes obligations
These are obligations arising from principle of jus cogens. The Prosecutor v Anto Furundzija described these obligations as owed to all other members of the international community. The violations of such an obligation simultaneously constitutes a breach of the correlative right of all members of the international community. 
Torture is a peremptory norm; therefore, there should be no derogation of this right in any situation, even in instances of public emergency, a state of war, a threat of war, or internal political instability. This exists in International Law statutes and as a Customary International Law specifically Article 2 of the Convention Against Torture (CAT).
The Convention Against Torture (CAT) defines torture under article 1 as any act internationally inflicted by a public official or a public officer acting in an official capacity to a person that instills severe pain physically or mentally meant to punish him or her for an act they are alleged to have committed or to intimidate or coerce him or her on reasons based on discriminations of any kind. This is the same definition under the Rome Statute of the International Criminal Court.
Article 5 of The Universal Declaration of Human Rights prohibits torture. The same is echoed under The International Covenant on Civil and Political Rights (ICCPR).
The Human Rights Committee has confirmed the same in its General Comment No.20 on article 7 (A/44/40) in its paragraph 3 which stipulates that;
“No justification or extenuating circumstances may be invoked to excuse a violation of article 7 (The International Covenant on Civil and Political Rights) for any reasons, including those based on an order from a superior officer or public authority”
Victims of torture are to be accorded means of redress and adequate compensation including rehabilitation and in case of his death, their dependants are to receive the compensation.
Article 2 of United Nations Convention on the Prevention and Punishment of the Crime of Genocide defines genocide as any acts that are committed with intent to destroy in whole or part of national, ethnical, racial or religious groups. This entails;
- Causing serious bodily or mental harm to members of a group.
- Killing members of the group.
Nothing authorizes a State Party to derogate from any obligation assumed under the provisions of the Convention on the Prevention and Punishment of the Crime of Genocide.
In the case of Prosecutor v Akayesu, the International Criminal Tribunal of Rwanda, Trial Chamber stated that; “the crime of genocide exists to protect certain groups from extermination or attempted extermination”.
In the case of Bosnia and Herzegovina v Serbia and Montenegro
Bosnia and Herzegovina had multiethnic population consisting of large numbers of Serbs, Croats and Muslims, even though Muslims were the largest.
The State seceded in April 1992 resulting to armed conflict between the ethnic groups. Bosnia and Herzegovina filled an application alleging genocidal attacks against it.
The court held that Republic of Yugoslavia (Bosnia and Herzegovina) should;
“……. ensure that any military, paramilitary or irregular armed units which may be directed or supported by it, as well as any organizations and persons which may be subject to its control, direction or influence, do not commit any acts of genocide……. whether directed against any other national, ethnical, racial or religious groups.”
The I.C.J agreed that on July 1995 Srebrenica massacre deserves the label of genocide.
Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v Russian Federation)
United States of America instituted this suit through declaration of intervention under article 63 of the statute on 7th September, 2022
Article 9 of United Nations Declaration of Human Rights and the International Covenant on Civil and Political Rights prohibits arbitrary arrests and incarcerations.
The case of Ahmadou Sadio Diallo (Republic of Guinea v Democratic Republic of the Congo)
Guinea filed an application in 1998 before the ICJ against the Democratic Republic of Congo in respect of serious violations of international law on the person of Ahmadou Sadio Diallo, a Guinea national. Mr. Ahmadou was arbitrarily arrested and imprisoned by the authorities of DRC after residing in DRC for 32 years.
The Court held that, in respect to the circumstances in which Mr.Ahmadou was arrested, it violated article 9, paragraphs 1 and 2 of the International Covenant on Civil and Political Rights.
The doctrine of jus cogens is important as it protects the fundamental interest of the international community, and a breach of it is considered a crime of the community that commits it as a whole.
L.L.B Hons, The Catholic University of Eastern Africa. Currently undertaking a Post-Graduate Diploma in Law at Kenya School of Law.
 Article 1, The Universal Declaration of Human Rights, 1948
 ICTY Appeals Chamber, Prosecutor v Anto Furundzija, Case No. IT-95-17/1-A
 Claire de Than, Shorts E, International Criminal Law and Human Rights, Sweet and Maxwell, 2003, page 9,
 Article 7, Rome Statute of the International Criminal Court
 ICTY Appeals Chamber, Prosecutor v Anto Furundzija, Case No. IT-95-17/1-A
 Article 4(2), The International Covenant on Civil and Political Rights (ICCPR)
 Article 2, Rome Statute of the International Criminal Court
 Article 7, The International Covenant on Civil and Political Rights (ICCPR)
 Article 14, The United Nations Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment of 1984(CAT)
 Article 6, Rome Statute of the International Criminal Court.
 Article 6(3) of the International Covenant on Civil and Political Rights
 Prosecutor v Akayesu, Case ICTR-96-4-T, International Criminal Tribunal for Rwanda, September 2, 1998.
 Case Concerning Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia– Herzegovina v Yugoslavia) (2007) ICJ 2
 The Case of Ahmadou Sadio Diallo (Republic of Guinea v Democratic Republic of the Congo), 2007 ICJ 653 (Order of June 27)