Opinio Juris - https://www.youtube.com/watch?v=TkR4j43Qmms

Pacta Sunt Servanda - https://www.youtube.com/watch?v=CPftp4WnmVQ  

Sources of International Law - https://youtu.be/xxCGE8fpVE0

Telegram: https://t.me/Legal_Talks_by_DesiKanoon

YouTube Channel: https://www.youtube.com/channel/UCMmVCFV7-Kfo_6S42kPhz2w

Apple Podcasts: https://podcasts.apple.com/us/podcast/legal-talks-by-desikanoon/id1510617120

Spotify: https://open.spotify.com/show/3KdnziPc4I73VfEcFJa59X?si=vYgrOEraQD-NjcoXA2a7Lg&dl_branch=1&nd=1

Google Podcasts: https://podcasts.google.com/feed/aHR0cHM6Ly9mZWVkcy5zaW1wbGVjYXN0LmNvbS84ZTZTcGREcw?sa=X&ved=2ahUKEwiuz4ifzpLxAhVklGMGHb4HAdwQ9sEGegQIARAD

Amazon Music: https://music.amazon.com/podcasts/4b89fb71-1836-414e-86f6-1116324dd7bc/Legal-Talks-by-Desikanoon 

Opinio Juris - https://www.youtube.com/watch?v=TkR4j43Qmms 

Pacta Sunt Servanda - https://www.youtube.com/watch?v=CPftp4WnmVQ 

Telegram: https://t.me/Legal_Talks_by_DesiKanoon

Latin Term – Meaning – “Opinion that an act is necessary by rule of law” or opinion of law. It is considered to be a belief that the practice is obligatory. This belief in the mandatory nature the conduct or practice may be termed Opinio Juris. 

Importance and Relevance – To decide whether a custom has become a source of International Law or not.

What is Custom? 

‘Custom’ is one of the many sources of International Law. It means a long established and commonly adopted practice that has acquired the force of law. 

Also finds mention in Article 38 (b) of the ICJ Statute that states that International Courts must apply international customs in their decisions, wherever possible and wherever it is a general practice accepted as law either in domestic laws or treaties or international agreements. 

Three types – general, regional and local. 

General Customs are followed in most of the places and jurisdictions. 

Regional Customs are followed in a particular region. North America may have its own Regional Customs distinct from South America or Asia. 

Local Customs have limited influence in a geographical area. India Pakistan and Sri Lanka may have a local custom that may not be followed anywhere else. 

The existence of a custom can be deduced from the practice and behaviour of states. Such custom becomes part of International Law when it is a State Practice and opinio juris. 

State Practice + Opinio Juris = New Customary Rule of International Law 

Four Steps 

1. Establish existence usage of a practice or conduct. 

2. Existence of State Practice 

3. Existence of Opinio Juris 

4. 1 +2 + 3 = New Custom

If all three are present, the practice or conduct becomes a new customary rule of International Law. 

1. Step 1 - How to establish existence of usage of a practice or conduct? When a country contends existence of a practice or conduct, it usually gives evidence in form of newspaper reports, statements by government leaders, mentions particular provisions in some law.

2. Step 2 - If such an existence is established, then the next step is to look into State Practice. State Practice simply means how states behave in practice. This practice can be found in their legislation, judicial decisions, administrative acts, official publications, treaties etc. Basically, it covers any act or statements by a state from which its existence as a customary law may be inferred.

3. Step 3 - Once State Practice is established, then the presence of opinio juris is to be seen. To ascertain such presence of Opinio Juris, the behaviour of the state towards that conduct or practice is seen. If the states make that practice or conduct legally obligatory or codify it or make it a legal right, then that conduct, or practice can be said to satisfy the ingredients of ‘Opinio Juris’ 

4. Step 4 - If existence of usage of a practice or conduct satisfies the dual requirements of State Practice and Opinio Juris, it becomes a valid ‘custom’ in International Law and the Court may decide accordingly. 

Issues faced by the Court in deciding presence of Opinio Juris 

1. Countries may exert pressure to make a practice a custom but views of countries with greater power does carry greater weight as politics or power cannot be divorced from law.

2. Unsubstantiated and unilateral claim by a state regarding existence of a custom cannot be accepted. It is the international context that plays a vital role in the creation of custom. 

3. Unsubstantiated and unilateral claim by a state regarding the existence of a custom are not accepted. It is the international context that plays a vital role in the creation of custom.

4. In new areas of law, Opinio Juris may be quickly or even instantaneously established because of the newness of the situation involved and lack of contrary rules. However, in traditional areas of law, it is more difficult to establish a custom as it has to be done through series of usages. Custom should mirror the perception of the majority of states.

Important Case Laws

1. Lotus Case

2. North Sea Continental Shelf Cases

3. Nicaragua v. United States 

4. Germany v. Italy

5. Asylum Case (Peru v. Colombia) 

1. 1958 – The United Nations Office for Outer Space Affairs (UNOOSA) is an office of the U.N. Secretariat that promotes and facilitates peaceful international cooperation in outer space. It is part of the UN that was established in the year 1945. If aliens actually visit the Earth, this will be the competent organization to deal with the same. Visionary approach of United Nations.  

2. 1960 – Establishment of Latin American Free Trade Association (LAFTA) by the Treaty of Montevideo. This treaty provided for new foreign investment rules and restrictions on operations of foreign firms in Latin American countries. It was later transformed into Latin American Integration Association. Currently, it has 13 member states.  

3. 1967 – Establishment of Association of Southeast Asian Nations (ASEAN) initially as a security association since at that point of time, entire Southeast Asia was beset with conflicts. It is currently a political and economic union of 10 member states including Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines and Singapore.  

4. 1967 – Signing of the Outer Space Treaty or the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies. Currently, there are 113 parties to this convention. Key provisions of the Outer Space Treaty include prohibiting nuclear weapons in space; limiting the use of the Moon and all other celestial bodies to peaceful purposes; establishing that space shall be freely explored and used by all nations; and precluding any country from claiming sovereignty over outer space or any celestial body.

5. 1969 – Adoption of Vienna Convention on the Law of Treaties (VCLT) that introduced the concept of ‘jus cogens’ in International Law. VCLT is one of the most important treaties in International Law. Currently, there are 116 parties to this convention.  

6. 1972 – United Nations Conference on the Human Environment at Stockholm, Sweden. The United Nations Environment Programme (UNEP) was created as a result of this conference. Around 122 countries attended it. Its success lies in the fact that in 1972, environmental governance was not seen as an international priority and still it was able to bring on board so many countries.  

7. 1979 – Signing of the Moon Treaty or the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies. Currently, 18 states are parties to the treaty. Its primary objective of is to provide the necessary legal principles for governing the behavior of states, international organizations, and individuals who explore celestial bodies other than Earth, as well as administration of the resources that exploration may yield.  

8. 1985 – Establishment of the South Asian Association for Regional Cooperation (SAARC). It is a regional intergovernmental organization and geopolitical union of states in South Asia aiming to accelerate the process of economic and social development in its member states through increased intra-regional cooperation. Its member states are Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.  

9. 1991 – Birth of Mercosur, a South American trade bloc established by the Treaty of Asunción. Mercosur's purpose is to promote free trade and the fluid movement of goods, people, and currency. Its members are Argentina, Brazil, Paraguay, and Uruguay.

10. 1995 – Birth of World Trade Organization (WTO) through the Marrakesh Agreement. It replaced the General Agreement on Tariffs and Trade (GATT) that was established in 1948. It is an intergovernmental organization that regulates and facilitates international trade. Currently, it has 164 member states.  

11. 1996 – Formation of Shanghai Five that later on succeeded as Shanghai Cooperation Organization (SCO) in the year 2001. It is a political, economic and security organization. Its member states are China, India, Kazakhstan, Kyrgyzstan, Pakistan, Russia, Tajikistan and Uzbekistan.

12. 1998 – The International Criminal Court (ICC) is established under the Rome Statute, adopted by 120 States on 17 July 1998 during the United Nations Diplomatic Conference of Plenipotentiaries on the Establishment of an International Criminal Court in Rome and enters into force on 1 July 2002. 

1.  1815 – Congress of Vienna – Series of international diplomatic meetings to discuss a new European order post the downfall of Napoleon that led to agreements on national boundaries within Europe, Neutrality Pacts, freedom of navigation.  

2.  1823 – Monroe Doctrine by James Monroe, then President of US - Any intervention by external powers in the politics of the Americas is a potentially hostile act against the US.  

3.  1824 – Calvo Doctrine –  Jurisdiction in international investment disputes lies with the country in which the investment is located. (Carlos Calvo, Argentine Jurist). Used mostly in International Investment Law.  

4.  1842 – Treaty of Nanking – Ended the First Opium War between Britain and Qing Dynasty – Its provisions involved cession of Hong Kong to the crown. Was considered an unequal treaty.  

5.  1864 – First Geneva Convention for the Amelioration of the Condition of the Wounded in Armies in the Field.  

6.  1865 – Establishment of International Telegraph Union to deal with international interconnection, standardization of equipment, tariffs etc.  

7.  1871 – Sino-Japanese Friendship and Trade Treaty – Mutual pledge for friendship and cooperation, exchange of ambassadors, trade related provisions.  

8.  1899 – First Hague Peace Conference – Establishment of Permanent Court of Arbitration.  

9.  1914-1918 – First World War

10.  1919 – Treaty of Versailles – Disarmament of Germany, payment of reparations by Germany, territorial concessions etc.  

11.  1920 – Paris Peace Conference – Establishment of League of Nations – a worldwide intergovernmental organization to maintain world peace.  

12.  1920 - Establishment of Permanent Court of International Justice.  

13.  1923 - Establishment of the Hague Academy of International Law  

14.  1928 – Kellogg-Briand Pact – International Agreement on peace – was aimed at preventing the second world war.  

15.  1939-1945 – Second World War

16.  26.06.1945 – Signing of Charter of United Nations  

17.  18.04.1946 – Replacement of Permanent Court of International Justice by International Court of Justice.  

18.  10.12.1948 – Adoption of Universal Declaration of Human Rights by UN GA.