The answer to the question 'Why States obey International Law?' has perplexed many theorists because the persuasive nature of international law itself has been questioned several times in different domains. Like most laws, international rules are rarely enforced but usually obeyed.

1 Indeed, the very way that the compliance question has been treated over the years as, in turn, a religious, moral, philosophical, political science, process, and now empirical question, itself provides a fascinating window into how internationalists have chosen to think about the role and function of international law.

2 Inspite of such criticism, today, international law becomes an important part of the running systems across the entire world because it interconnects boundaries and provides a platform for putting forward their ideas, thoughts, and faith. It sets out certain rules and norms for governing this relationship globally. If such a law would have been absent in this globalised world then a state of mayhem would occur.

In common speech and the speech of politicians and diplomats, states are corporate agents that have intentions, interests, and obligations; they can declare war, make promises, and form alliances; they can grow, shrink, divide, and merge. 3 But the question, however, arises of whether the should State comply with international law. if yes, then how? if not, then why?

An act of consent is not a sufficient condition for creating an obligation: A promise, which is an act of consent, is not a legal obligation.4 What is necessary for an act of consent to create a legal obligation is the satisfaction of additional formalities which themselves are not the creation of the parties.5 These formalities are provided externally by domestic or international law and are not the result of consent by individuals (in domestic law) or the state (in international law).6

Harold Koh has identified 'why states obey International law?' He argues that Franck's Fairness approach and Chayeses' Managerial approach are traditional and in modern times with the evolvement of international law, the reason behind its compliance by the States has also taken a
sharp turn. He basically supports Transnational Legal Process which shall be discussed further.

1. Interpretation Of Global Norms Leads To Internalisation:

   Harold Koh argues that when States start communicating with each other and interpreting the
   global norms that are being implemented then by this the parties internalise the new interpretation of the international norm into each other's internal normative system. This results in the revival of a new internal value set which becomes a basis for further transactional interests and reconstitutes the identities of the parties as well.
    

2. Interest And Identity Of The States:

   The international norms that are set often find their way into domestic laws. The States accept such norms because it reshapes their identity of it and also serves their self-interest. In the words of Harold Koh, such norms aid in linking the state interest, national identity and international society together.
    

3. Interaction, Interpretation And Internalisation:

   As the different actors of different States interact with each other with the help of International organisations, business entities, and transnational entrepreneurs, it leads to more acceptance of international law. According to Harold Koh, these organisation aids in internalising and interpreting the norms which lead to obeyance of it.
    

4. Transparency:

   States start obeying international laws to keep transparency as these laws have opened the boundaries and nothing can be kept a secret. Hence, to keep its domestic affairs transparent and as well keep track of other states' territory activities, States automatically obey international laws. They understood compliance with international law to result almost entirely from the functional benefits such compliance provides.7

The justifications mentioned above have evolved over different periods. It started when international laws were not even recognised and now has reached a stage where we are talking about why States obey them. The evolution as mentioned by Harold Koh is discussed further.

1. Ancient and Primitive International Law:
   In this period, international law was considered a part of a semi-theological reference. Only treaty law had legal force because it was considered a sacrament.In the medieval period, there was no difference between municipal and international law. Hence, there was no deliberation on why states should obey international law.
    
2. Traditional International Law:
   The concept of transborder obligations led to a shift in the meaning of international law. Customs and State practices came to be the primary sources of law. But there was no strict rule to comply with it. In this period no was one concerned whether States obey the law or not but the important focus was on what national rulers would do.
    
3. The Dualistic Era:
   From Natural Law to Positivism: Here, international law had started to be viewed as man-made laws. There were four views. Firstly, Jeremy Bentham coined the phrase "inter-national law." He initiated the era of dualistic theory where compliance with domestic and international law diverged. This period bought up the question that why States obey. Secondly, John Austin declared international law, not a law because they are not enforced by sovereign coercion. Thirdly, Hobbesian utilitarian and rationalistic starnad which acknowledged that States sometimes follow international law. Fourthly, liberal Kantians stated States only obey international law when it served their self-interest. The first World War interrupted this momentum and forced scholars to reflect on the new legal order that emerged from the Treaty of Versailles. This led the community to promote compliance with international norms.
    
4. The era of Institutions:
   In the wake of World War II, the importance of independent Institutions governed by multi-lateral treaties was realised. Hence, many institutions were established like the United Nations, the General Agreements on Tariffs and Trade and others. The difference between public and private law was identified. The theory by John Austin was rejected. Few scholars attempted to answer 'why States obey?' It was seen in Louis Henkin's "How Nations Behave" in 1968.19 Two schools emerged in this era ie The New Haven School which viewed international law as a set of normative values and the second was the International Legal Process School for which international law was a set of rules promulgated by a pluralistic community of States. But both were unclear about why States should obey international law.
    
5. Interdependence and Transnationalism:
   By this era, the importance of international law was recognised and regular interactions of States were seen. The major theoretical work on compliance in this era was done by political scientists Robert Keohane, Robert Axelrod and Oran Young. Different schools emerged to answer the question of Why States should obey international law? The term Transnational legal process was coined by Steiner and Vagt's casebook wherein internalisation, interpretation, and interaction would lead to compliance. The rationalists said it is necessary to comply because of the functional benefits. Another theory stated that international law is obeyed "because they perceive the rule and its institutional penumbra to have a high degree of legitimacy."
    
6. After the Cold War:
   The New World Order: International law now comprises a complex blend of customary, positive, declarative and soft law which seeks not simply to ratify existing practice, but to elevate it. Three compliance literation was introduced. First, to fulfill self interests;
   Second, to make a national identity; Third, to constructive rules and norms.

Therefore, we saw how the justifications evolved through the various period. It would not be wrong to say that the question is still evolving and would continue to do so. The new theories would enlighten many. These trends have restructured the planetary stage on which international law performs, making way for what Franck calls "the post-ontological era" of mature and complex international law.

End Notes:

1. Hans J. Morgenthau, 'Politics Among Nations: The Struggle for Power and Peace' (1954) SAGE 249
2. Harold Hongju Koh, 'Why Do Nations Obey International Law?' (1994) 106 The Yale Law Journal 2599.
3. Eric A. Posner, 'Do States Have a Moral Obligation to Obey International Law?' (2003) 55 Standford Law Review
4. Ibid.
5. Ibid.
6. Edward Hallet Carr, The Twnety Years' Crisis 1919-1939 (3th edn, Harper and Row 1964).
7. Robert O. Keohane, Jr., International Institutions: Two Approaches (Oxford University Press 1988).