International law is a complex and multifaceted area of the global legal system that seeks to regulate relations between states and other international actors for peaceful interaction. It covers relevant areas of the discipline between diplomatic relationships, commercial treaties, protection of human beings, environmental regulations, etc. Understanding the sources of international law requires a closer look at both its primary and secondary sources. This comprehensive guide delves deep into these sources to provide you with their interpretation of how international law is developed, interpreted, and applied.

The Primary Sources Of International Law

1. Treaties and Conventions:Treaties and conventions are the most formal and explicit sources of international law. They are written agreements between states or other international organizations that are legally binding. They can either be bilateral, between two states, or multilateral, involving many states. Examples are:
   • Charter of the United Nations[1]: This fundamental treaty recognizes the United Nations and stipulates its purposes, principles, and structure. It lays down the cornerstone of modern international relations and international law.
   • The Geneva Conventions[2]: A body of pacts and protocols that establish international law norms for humanitarian treatment in the event of armed conflicts. It is in this respect that the conventions safeguard people who are not taking part in hostilities, like civilians, medical staff, and prisoners of war.
   • The Paris Agreement[3]: This is a multilateral environmental agreement targeted to fight the threats of climate change. The agreement aims at keeping global warming well below 2°C above pre-industrial levels, at the same time restricting the increase to 1.5°C.
   Treaties and conventions would have to be negotiated, signed, and ratified by the participating states, hence of a formal nature and consensual acceptance of being bound. Once in force, they become a primary source of rights and obligations in international law.
    
2. Customary International LawCustomary international law arises from the continuous and general practice of states, which follow such practice because they believe it is a legal obligation (opinio juris). Unlike in regard to treaties, customary international law is not written or codified though it is still considered accepted. For a customary practice to be considered customary international law practice, the requirements are that it must be general and constant state practice followed by the belief that such practice is required by the principle of law.
   • Principle of Non-Refoulement: The principle forbids states from returning refugees or asylum seekers to territories where, if such a step were taken, their lives or freedom would be threatened. It is among the most basic principles within the international law concerning the protection of refugees.
   • Immunity of State Diplomats: A principle granting diplomats safe passage, not embracing prosecution or lawsuit in the host country's laws; It is an indispensable practice that would see to it that diplomatic relations are accorded the right environment and is encompassed within the Vienna Convention on Diplomatic Relations.
   It is here that customary international law, a major source of international law, plays its important role to fill in the gaps when treaties may not exist or may not detail the desired information. This is, at the end of the day, a source that is changeable, i.e., changes over time—it is dynamic—through changes in state behavior and international norms.
    
3. General Principles of LawGeneral principles of law are basic rules of law that receive their validation from a vast majority of national legal systems. Their serving as a source of international law comes in handy when treaties and customary law provide limited guidance. Their development is derived from legal ideas that are common in most domestic legal systems.
   • Principle of Good Faith: The principle connotes that the parties to the treaty are to deal with each other fairly and honestly and to fulfil the undertakings in good faith. It is a basic concept for both domestic and international law.
   • Equity: The principle that provides for justice and justness in the dispensation of the law, allowing flexibility and discretion so that its application is not based rigidly on the result of an unjust effect.
   These general principles of law are general points that form the basis for various legal systems to interpret and apply international law; they promote consistency and coherence across varying systems.
    
4. Judicial DecisionsInternational courts and tribunals play a crucial role in the development and interpretation of international law through their judicial decisions. The decisions provide guidance to application that is authoritatively binding but at the same time open space for a dynamic jurisprudence in the international arena.
   • International Court of Justice: The principal organ of the United Nations for dealing with disputes between states and rendering an advisory opinion on questions of law, in accordance with the United Nations and its specialized organs. Settlement and decisiveness of ICJ issues are binding on parties in dispute and have a prescriptive weight in law doctrine elucidation of international law.
   • ICC (International Criminal Court): It is a permanent court which is prosecuting and judging people on the cases of genocide, war crimes, and crimes against humanity. The Policies of ICC ensure the development of international criminal law and the enforcement of individual responsibility.
   • Ad Hoc Tribunals: Temporary institutions, usually courts, created to deal with issues of particular conflicts or topics. For example, the International Criminal Tribunal for the former Yugoslavia (ICTY) and the International Criminal Tribunal for Rwanda (ICTR). They have been very important for the development of international criminal law and have set a very important precedent in the process.
   Judicial decisions serve not only to fix individual cases but also to clarify and interpret general norms of law with the effect of contributing to the steadiness and predictability of international law.
    
5. Scholarly Writings The works of legal scholars represent one of the liveliest sources that impact international law. They give invaluable points and arguments that influence it. Works of scholars may help in clarifying normative principles in the law, suggesting new interpretation, or going to the extent of criticism of existing norms and practices. International law has been well enriched and developed by the scholarly contributions of many figures. Amongst them, Hugo Grotius, Emer de Vattel, and Hersch Lauterpacht are highly notable. Their scholarly papers have remained an important source for the discourse and understanding of international law. While not being binding per se, or in the technical sense, scholarly writings are often cited by courts, tribunals, and international organizations as persuasive authority. They help to point out new trends, analyze state practice, and point to normative changes.
    
6. Resolutions and Declarations of International OrganizationsThe international resolutions and declarations, originating from international organizations, for example, the United Nations, might impact international norms and states' behaviors, though they lack a legal binding. In a real sense, these mechanisms express the international community's collective will and consensus on different issues.
   • UN General Assembly Resolutions: Although non-binding, they carry a lot of political and moral weight. They are often on some of the critical issues affecting the globe, from human rights, to disarmament, to sustainable development. General Assembly resolutions can contribute to the formation of customary international law when they tend to reflect views and practices supported by majority states.
   • Declarations: The pronouncement of the principle of intentions of international organizations, for meant example, although the Universal Declaration of Human Rights[4] is not a legally binding document, it provides standards for human rights of a basic nature and has laid down the founding influence on the development of the rules of human rights within international law.

Resolutions and declarations can instigate legal and policy changes. They lend direction to states on their international behaviors and help foster and develop international norms.

Conclusion
International law is a dynamic and changing body because its sources are very much in tune with the very multidimensional, pluralistic, and interdependent world our community has become. Treaties and conventions provide that which is formal in the way of international obligations and rights, whereas, in customary practices and general principles, there lies the exercise of flexibility and adaptability. Judicial decisions, scholarly writings, and international resolutions further enrich and inform the application of international law.

Understanding these sources helps unveil how international norms and rules get developed, interpreted, and applied, further encouraging a just and orderly international system. With complex global challenges, ever more resources of international law are to be the set of guiding principles for international relations to develop peacefully, securely, and cooperatively among and between states and other international actors.

End Notes:

1. Charter of the United Nations (signed 26 June 1945, entered into force 24 October 1945) 1 UNTS XVI.
2. Geneva Convention:
   • Geneva Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field (adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS 31.
   • Geneva Convention (II) for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea (adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS 85.
   • Geneva Convention (III) Relative to the Treatment of Prisoners of War (adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS 135.
   • Geneva Convention (IV) Relative to the Protection of Civilian Persons in Time of War (adopted 12 August 1949, entered into force 21 October 1950) 75 UNTS 287.
3. Paris Agreement (adopted 12 December 2015, entered into force 4 November 2016) UNTS No. 54113.
4. Universal Declaration of Human Rights (adopted 10 December 1948) UNGA Res 217 A(III).