Law is especially a set of rules which regulates behavior and respects the ideas and preoccupations of the society within which it  functions. The basis behind the law is that Peace and  order is necessary and chaos are crucial to a just and stable existence. Law is that element which binds the members of the community together in their adherence to recognized values and Standards. A Municipal Law should be based on certain specific set of values, social, economic and political and these values form the base for legal framework which order the life in that environment. Municipal Law regulates relation between individuals.

International Law respects first and foremost the basic state oriented character of world politics, units of formal independence benefiting from equal Sovereignty in law and equal possession of the basic attributes of statehood have succeeded in creating a system enshrining such values. International law regulates relations among Nation States. This article generally focuses the major legal major  rules and norms practiced in customary International law.

1. Pacta Sunt Servanda
   Regulates the relationship between two or more countries that enter into an agreement.
   Principle of good faith.
   When a Treaty is entered upon between two or more States, it constitutes diplomatic relations and gives rise to several changes in the domestic laws as well.
   Article 26 of the Vienna Convention on the law of treaties, 1969.
    
2. Rebus Sic Stantibus
   Things thus standing refers to a situation where a contract cannot be withdrawn from  or terminated as long as the conditions and circumstances surrounding the contract have not fundamentally changed.
   It is a form of doctrine in international law.
   Article 62 of the Vienna Convention on the law of treaties 1969.
   It is not expressly mentioned in any International legal framework or instrument. This doctrine serves the objective of protecting state interests.
    
3. Jus Cogens
   It is a peremptory Norm or rule that cannot be deviated while framing any International law or agreement.
   It means a law which is compelling or binding.
   Article 53 of the Vienna Convention on the law of treaties resonates Article 13 (2) of the constitution of India.
   Article 64 of the convention expands the scope jus cogens by stating that if a new principal or norm is declared to be jus cogens , the existing  treaties must comply with that as well.
    
4. Utipossidetis
   It is a principle in international law that territory and other property reminds with its Possessor at the end of a conflict unless otherwise provided by the Treaty.
   It means ‘as you possess’.
   The essence of the principle lies in its primary aim of securing respect for the territorial boundaries at the moment when independent is achieved.
   Relevance of utipossidetis.
   For the determination of maritime areas like historic waters.
   For the succession to treaties establishing Maritime boundaries.
    
5. Ultravires
   Ultravires acts can also be defined as any excessive use of Corporate power that has been granted.
   These acts cannot be legally defended in court.
   It means beyond the power.
   Ultra vires acts fall outside the powers that are specifically listed in a corporate character or law.

All these are the major legal jargons recognized in international law. International organizations have international legal personality and can participate in international relations in their own capacity, independently of their member states.

Change is the only rule which is unchangeable. One of the major problems of International law is  to determine when and how to incorporate new standards of behavior and new realities of life into the already existing framework so that on the one hand, the law remains relevant. The Scope of International law today is immense.

From the regulations of space expeditions to the question of the division of ocean floor, and from the protection of human rights to the management of International Financial System its involvement has spread out from the primary concern of maintenance of peace and security to all the interests of contemporary International life.