Introduction to international law, subjects and sources of international law and background material.

Who is a subject of international law?


NB: The aim of this post is to simplify an area of international law that may be confusing to students of international law. This is not comprehensive and you are encouraged to read further. Textbooks accessible online include Dixon and Shaw..


Some questions that are relevant to the study of international law include who can create international law; who has rights, duties, and powers under international law (or international legal personality); and who is regulated (governed), directly or indirectly, by international law.

International legal persons – also called subjects of international law – are capable of possessing, exercising and/or enforcing varied degrees of rights and duties under international law. They may also contribute to the creation of international law.

International legal persons can be broadly categorized as States and non-State actors (see below). As opposed to these subjects, there are also other “participants” of international law, who cannot directly claim and exercise their rights, except through States (for example, private companies), and those who influence the development of international law even if they are not subjects (for example, groups that influence the creation of international anti-terrorism treaties).

States , at a conceptual level, have equal rights and duties under international law by virtue of the principle of sovereign equality.  Others – non-State subjects – have degrees of rights and duties that vary amongst their different categories (for example, individuals as opposed to international organizations), and within their own category (for example, different international organizations have different rights and duties).

Dixon – “A subject of international law is a body or entity recognized or accepted  as being capable, or as in fact being capable, of possessing and exercising  international law rights and duties (p. 116).”



The moment an entity becomes a State (see criteria for statehood), it becomes an international legal person and acquires international legal personality. States are the original subjects of international law – i.e. international law was created to regulate relations between States.


Non-State actors with international legal personality include individuals, armed groups involved in conflicts (see here, here and here), and international organizations (see here for the UN and here for the EU).

While it can be confusing, some laws, for example, international humanitarian law, imposes obligations on all parties to a conflict (even if that party is also considered as a terrorist group by one or more States) and provides certain protections for individuals, irrespective of their ideologies or atrocities committed. For example, it is prohibited to torture or kill an individual in detention, whoever that individual maybe. Armed groups also have obligations under international humanitarian law to protect those detained in their custody.

There is still some debate on whether international non-governmental organizations, ad-hoc coalitions made of States during an armed conflict (as opposed to individual States), and multinational companies are, or should also be considered as, subjects of international law.


An international organization is defined as “an organization (1) established by a treaty or other instrument (2) governed by international law and (3) possessing its own international legal personality.  International organizations (4) may include as members, in addition to States, other entities.” (A. 2 (a) Articles on the responsibility of international organizations). The United Nations and the World Trade Organization are examples of international organizations. 




It is possible to say that States have original personality and non-State actors have derived personality. This is because States become international persons the moment they are States. Other subjects derive their personality through other means – for example, for organizations, the extent of their rights and duties under international law may be described in their constitutions/charters/treaties that establish the organization.


The rights, powers, and duties of different subjects change according to their status and functions. For example, an individual has the right of freedom from torture under international law. States have a duty under international law not to torture individuals or to send them to a country where there is a likelihood of that person being tortured. This right exists under treaty law, for example, under the International Covenant on Civil and Political Rights and under customary international law. The Convention against Torture and Cruel, Inhuman and Degrading Treatment places obligations on States not to torture and to extradite or prosecute those who commit torture. 

Legal personality also includes the capacity to enforce one’s own rights and to compel other subjects to perform their duties under international law. For example, this means that a subject of international law may be able to:

(1) bring claims before international and national courts and tribunals to enforce their rights.

(2) have the ability or power to come into agreements that are binding under international law (for example, treaties).

(3) enjoy immunity from the jurisdiction of foreign courts (for example, diplomatic immunity).

(4) be subject to obligations under international law (for example, obligations under international humanitarian law).

Remember that all subjects of international law do not have the same rights, duties and capacities. For an example, a diplomat has immunity before foreign courts because he is an agent of the sending State. See blog posts and media articles on the US- India diplomatic/ consular incident involving Devyani Khobragade here, here and hereOne State can bring a claim against another State before the International Court of Justice to enforce the rights of that State or on behalf of individuals. An individual on his own can’t bring a claim against a State before the ICJ. In other words, States have all the capacities mentioned above and individuals have only a few.

© Ruwanthika Gunaratne and Public International Law at, 2008 – 2018.


What is public international law?

© Ruwanthika Gunaratne and Public International Law at, 2008 – present. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Ruwanthika Gunaratne and Public International Law with appropriate and specific direction to the original content.


  • Public international law  is the body of rules that is legally binding on States in their interactions with other States, individuals, organizations and other entities. It covers a  range of activities; such as, diplomatic relations, conduct of war, trade, human rights and sharing of oceanic resources. ✐ Give examples of other areas of international law.
  • Traditionally,  international law regulated interactions between States. For example, it determined how a State should treat foreign diplomats who are in its country or when a State should declare war against another State.
  • International law sets out legal obligations, responsibilities and rights of one State against another. This aspect of international law is based on sovereign equality. In other words, each State is a sovereign and each State is equal and independent of all other States. This means that when international law regulates the relations between States, it applies equally to all States.  ✐ Do you think that all States are equal in their relations with each other and international law applies equally to all States? What example would you provide to support your answer? See here for criticism of the US’ and China’s approach to international law. 
  • International law also regulates relations between States and non-State actors; for example, individuals, international organizations and multinational companies. In the case of individuals, international law gives each individual certain rights. For example, international human rights law gives the individual a right not to be tortured. This means that a government cannot torture even someone they deem a terrorist to obtain information. International law also imposes on States certain obligations and responsibilities to protect individuals. For example, when States are at war, one State cannot target and kill innocent civilians of another State.
  • It important to remember that international law is not stagnant. It is evolving. International law covers diverse subjects and has multiple fields of application. For example, we find that international law applies, inter alia, to:  initiation of wars (laws relating to use of force); conduct of war (humanitarian law); diplomatic relations (diplomatic law); trade and investment; treatment of people (human rights law); ocean resources (law of the sea); protecting the environment (environmental law),  space law, and to certain crimes (international criminal law).

Reading material


© Ruwanthika Gunaratne and Public International Law at, 2008 – present. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Ruwanthika Gunaratne and Public International Law with appropriate and specific direction to the original content.