United Nations Human Rights Council:
“Reaffirming also that States must ensure that any measure taken to combat terrorism complies with their obligations under international law, in particular international human rights law, international refugee law and international humanitarian law, as applicable.”
Report of the Office of the United Nations High Commissioner for Human Rights:
“Cases of recruitment of children documented in this report were committed in the context of and associated with the internal armed conflict in Sri Lanka.”
United Nations High Commissioner for Human Rights Sri Lanka web page:
“During the period covered by the investigations, there existed an internal armed conflict, making necessary the application of international humanitarian law, in particular provisions of the Geneva Convention relevant to non-international armed conflicts, to measure the conduct in the conflict of both the Government and non-state armed groups.” 
United Nations Security Council Press Release:
The members of the Security Council strongly condemn the Liberation Tigers of Tamil Eelam (LTTE) for its acts of terrorism over many years, and for its continued use of civilians as human shields, and acknowledge the legitimate right of the Government of Sri Lanka to combat terrorism. 
There is a legal dispute in the United Nations (UN) for the definition of the past armed conflict in Sri Lanka and definition of the Liberation Tigers of Tamil Eelam (LTTE).
In the web page of United Nations High Commissioner for Human Rights Sri Lanka, the past conflict in Sri Lanka is defined as an internal armed conflict and the parties to the conflict are described as government, (Sri Lanka) and non-state armed group, (LTTE). In the report of the Office of the UN High Commissioner for Human Rights (A/HRC/30/CRP.2), the past conflict was described as internal armed conflict.
UN Security Council defined the past conflict in Sri Lanka as combat terrorism. In the mandate given to the UN Office of the High Commissioner for Human Rights for Sri Lanka (A/HRC/30/L.29) by the UN Human Rights Council also the situation was defined as combat terrorism.
When the legal accepted definition of the Office of the UN High Commissioner for Human Rights, for the past Sri Lanka conflict is different than the UN Human Rights Council and UN Security Council, as well as the definition for LTTE not as a terrorist group but a non-state armed group, some specific thoughts arises in minds, such as: the hierarchy in the UN, the responsibilities of the UN Office of the High Commissioner for Human Rights for the mandates given to him, the erga omnes character of combat terrorism, responsibility of the UN Office of the High Commissioner for Human Rights or any UN organ to the UN Global Counter-Terrorism Strategy, definition of terrorism in the UN conventions.
Part I – Definitions
Sometimes it is better to return back to all the definitions related to a dispute of defining a situation in law. To analyze the difference between the definitions “internal war” or “combat terrorism” in Sri Lanka, as well a “non-state armed group” and a “terrorist group”, all the definitions related to the main issue should be reviewed.
The view that some norms are of a higher legal rank than others has found its expression in one way or another in all legal systems. Also in international law propositions have consistently been made that there is a category of norms that are so fundamental that derogation from them can never be allowed. No doubt, the idea of peremptory norms , jus cogens  is older than modern international law itself.
The term jus cogens denotes a set of legal norms. According to the definition provided in Article 53 of the Vienna Convention of Treaties, a jus cogens nor] is a norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character.
The jus cogens norm typically to be a norm having a regulative character. According to often-used terminology, legal norms have either a regulative or a constitutive character. When a norm is used to identify some behavior or state of affairs as either prescribed, prohibited, or permitted, it is said to have a regulative character. When instead a norm is used to create an institutional fact it is said to have a constitutive character. For instance, a constitutive norm may be used for the purpose of establishing an international tribunal or defining some legally relevant concept. Clearly, the assumption underlying all previous writing on the topic is that jus cogens norms belong to the former category only. 
It is accepted by the international community that, norms of jus cogens protect the fundamental values of the international community, are hierarchically superior to other norms of international law and are universally applicable.
It is useful to point out that, in international law, the idea that some rules are peremptory and cannot be derogated from through ordinary means of law-making is exceptional. The majority of rules of international law fall into the category of jus dispositivum  and can be amended, derogated from and even abrogated by consensual acts of States. 
Obligation Erga Omnes
In its dictum on the Barcelona Traction case, the International Court of Justice (ICJ), gave rise to the concept of erga omnes obligations in international law. The ICJ adapted a similar idea to the field of law enforcement, by cryptically pointing to an … essential distinction between the regular obligations of a State and those … towards the international community as a whole. The latter, it went on, included obligations deriving … from the outlawing of acts of aggression, and of genocide, as also from the principles and rules concerning the basic rights of the human person, including protection from slavery and racial discrimination, which were … the concern of all States. And further: … In view of the importance of the rights involved, all States can be held to have a legal interest in their protection; they are obligations erga omnes. In its dictum on the Barcelona Traction case, the ICJ, as the primary judicial organ of the UN, gave rise to the concept of erga omnes obligations in international law. In this judgment the Court drew a distinction between the erga omnes obligations that a state has towards the international community as a whole and in whose protection all states have a legal interest, and the obligations of a state Vis-à-Vis another state. 
The Permanent Court of International Justice and the International Court of Justice have addressed the issue of the existence of a dispute in several cases. In the Movrommatis Palestine Concessions case the Permanent Court of International Justice gave the following definition:
“A dispute is a disagreement on a point of law, a conflict of legal views or of interests between two persons.” 
International Court of Justice in Interpretation of the Peace Treaties with Bulgaria, Hungary and Romania defined as:
“a situation in which the two sides held clearly opposite views concerning the question of the performance or non-performance of certain treaty obligations.” 
Internal War – Non-International Armed Conflict
A non-international or internal armed conflict refers to a situation of violence involving protracted armed confrontations between government forces and on or more organized armed groups, or between such groups themselves, arising on the territory of a State. In contrast to an international armed conflict, which opposes the armed forces of States, in a non-international armed conflict at least one of the two opposing sides is a non-State armed group.
The existence of a non-internatinal armed conflict triggers the application of international humanitarian law (IHL), also known as the şaw of armed conflict which sets limits on how the parties may conduct hostilities and protects all persons affected by the conflict. IHL imposes obligations on both sides of the conflict equally, thıugh without conferring any legal status on the armed opposition groups involved. IHL requires that two criteria be met for there to be a non-international armed conflict: the armed groups involved must show a minimum degree of organization and the armed confrontations must reach a minimum level of intensity. The fulfillment of these criteria is determined on a case-by-case basis, by weighing up a number of factual indicators. 
There is no real difference. The term “civil war” has no legal meaning as such. It is used by some to refer to a non-international armed conflict. Article 3 common to the Geneva Conventions – does not use the term “ civil war” but refers instead to “armed conflictş not of international character.”
The International Committee of the Red Cross generally avoids using the term “civil war” when communicating with the parties to an armed conflict or publicly, and speaks instead of “non-international” or “internal” armed conflicts, as these expressions mirror the terms used in common Article 3. 
Non-State Armed Group
A first influential definition of non-state armed group can be found in the Additional Protocol II to the Geneva Conventions: It is stated that the rules only apply to internal conflicts between a government’s armed forces “[…] and dissident armed forces or other organized armed groups which, under responsible command, exercise such control over a part of its territory as to enable them to carry out sustained concerted military operations and to implement this Protocol.” This definition is stricter than most other definitions and it requires an effective control over a territory. 
Definition of non-state armed groups has proven difficult owing to their many types and characteristics. There is no universally accepted definition. Generally speaking, non-state armed groups are defined as distinctive organizations that are (i) willing and capable to use violence for pursuing their objectives and (ii) not integrated into formalized state institutions such as regular armies, presidential guards, police, or special forces. They, therefore, (iii) possess a certain degree of autonomy with regard to politics, military operations, resources, and infrastructure. 
A non-state armed group is an organized group with a basic structure of command operating outside state control that uses force to achieve its political or allegedly political objectives. Such groups include ‘rebel groups’ and governments of entities which are not (or not widely) recognized as states. 
The extant scholarship on the definition of terrorism suggests that terrorism is a phenomenon that is distinct from other types of political violence. The distinguishing features include such elements as the targeting of unarmed civilians, the use of extra-normal violence, the desire by the terrorists to instill fear in the target population, or the intent to influence a broader audience beyond the immediate victims of the terrorist attack.
A terrorist group can be defined as any group that uses terrorism. There are different definitions of “terrorist groups” such as;
‘‘A terrorist group is defined as a collection of individuals belonging to a non-state entity that uses terrorism to achieve its objectives.’’
‘‘A terrorist group is defined as a group that uses terrorist tactics, meaning it deliberately targets civilians in pursuit of political goals.” 
“Organizations consisting of more than one person that engaged in violence with a political purpose aimed at evoking a psychological reaction in an audience that extended beyond the targeted victims.” 
‘‘Terrorist groups are organizations that rely, partially or exclusively, on [terrorism] to achieve their political ends.’ 
To be continued