Throughout history, there have been periods of fall and resurgence for natural law theory, which is based on the idea that there is an objective moral order exists in the natural world. This research study provides a thorough analysis of the natural law school's decline and revival following it from ancient philosophy to its modern manifestation. There are various factors that lead to the decline of natural law school.

The advent of positivism and the Enlightenment's emphasis on reason and empiricism in the modern age contributed to a skepticism about the idea of an unchanging, universal moral code. Natural law jurisprudence was also further marginalized within legal academia with the arrival of legal realism in the 20th century, which placed a strong emphasis on empirical observations of legal practice. However, in recent decades, natural law theory has seen remarkable growth despite of obstacles.

There are various reasons for this comeback. First, there is a growing interest in natural law as the basis for ethical and legal principles because of the frustration with legal positivism's limitations. Furthermore, discoveries in disciplines like neuroscience and evolutionary biology have shed light on the biological and psychological basis of moral reasoning, supporting the idea that natural laws are governed by inherent moral principles.

 Furthermore, the interaction of natural law theory with contemporary issues like human rights and environmental ethics has strengthened its relevance in legal and philosophical discourse. This paper attempts to provide a comprehensive view of the relevance of natural law theory in the modern era and its potential implication for legal theory and practice in the twenty-first century by looking at case studies and academic discussions.

Introduction
The natural law school of thought is a legal and philosophical theory that holds the universal set of moral principles present in nature which regulate human behaviour and help the development of just law. Natural law theory has its roots in the philosophy of the ancient Greeks and Romans and was subsequently expanded upon by theorists such as Thomas Aquinas, Hugo Grotius etc.

The word natural law is derived from the Roman word 'Jus Naturale' which means the system of law based on the idea of right and wrong[1]. Those who follow the philosophy of natural law are called naturalists. It is the unwritten body of moral principles that established the ethical and legal norms to regulate the conduct of human beings.

Natural law is the moral concept of jurisprudence which advocates that the law should be based upon the basis of morals and ethics. The Law must be focused on what is right. Natural law is not man-made law but inherent laws. They are derived from nature, divine sources and by reason.

Heraclitus: laid down the basis of natural law. Destiny, order and reasons of the world played important roles in the development of natural law. Nature is not just substance, but a relation, an order of things.

Aquinas: the natural law is nothing but the participation of eternal law in a rational creature. The primary objective of law is to be good and avoid evil. He divided law into four categories:

• Law of God
• Natural law
• Divine law or law of scriptures
• Human law or positive law

Natural law is an integral part of the divine law which reveals itself in natural reason. This is applied by human beings to regulate their affairs.

Grotius: natural law is based on the nature of man and his inward to live in society. He refers to human nature as the grandmother, natural law the parents and positive law the child. Natural law is irreversible and cannot be changed by God himself

Characteristics of Natural Law:

• Universal Principles: The fundamental tenet of natural law theory is the existence of moral standards that apply to all people universally, irrespective of their culture or religion.
• Rational inquiry: Proponents of natural law stress the significance of philosophical thought and rational inquiry in determining these moral precepts. Natural law theorists contend that moral truths may be determined by logical analysis and observation of the natural world, as opposed to depending only on religious dogma or legal precedent.
• Objective Morality: According to natural law theory, there is an objective morality that exists and is unaffected by personal preferences or views. This perspective holds that some behaviors are intrinsically morally good or bad based on their adherence to universal moral standards, regardless of whether individuals or societies approve of them.
• Relationship with positive law: Proponents of natural law theory frequently make a distinction between positive law and natural law. Positive laws can differ throughout communities and eras, but natural law is considered to be superior and unchangeable, offering a standard by which the legitimacy of positive laws can be judged.
• Justice and equity: Justice and equity are highly valued in natural law theory as these are the fundamental components of a just legal system.
• Human Rights: The idea of human rights is based on natural law theory. There are some fundamental rights that are inherent to human beings by their nature, such as the right to property, liberty, and life.
• Limitation on Government: Natural law jurists often advocate for limited government power, and it is a duty of government to uphold natural law and protect the rights of citizens.

Decline of Natural law School:

There are various reasons for the natural law school[3]:

1. Empiricism and Positivism: During the 17th and 18th centuries, the concept of empiricism and positivism shifted the focus of philosophy and law away from abstract towards empirical evidence. Empiricists and positivists argued against the idea of moral principles and favored of more empirical and scientific approach to understanding the human behavior:
   • Montesquieu (1689-1755): law must be influenced by the climate of the particular region including soil, religion, customs and commerce etc. his idea negates the doctrine of natural law.
   • David Hume (1711-1776): values and justice are not inherent in nature. He favours the firm and inflexible application of rules although those should be widely designed and changed with the circumstances.
2. Scientific Revolution: The authority of natural law theory, which was based on abstract reasoning and metaphysical principles, was challenged by the Scientific Revolution of the 16th and 17th centuries, which focused on empirical observation and experimentation.
3. Separation of Law and Morality: Legal positivism, which was developed by thinkers like Jeremy Bentham and John Austin, argued for a clear separation between law and morality, holding that the legitimacy of a law depends more on its source (such as legislative authority or social convention) than on its moral content. This viewpoint undermined the concept of natural law.
   • John Austin: He rejects the idea of natural law that it was ambiguous and misleading. According to him, the science of jurisprudence is concerned with the positive law. He opposed the natural rights of individuals against the state in the sense that all rights are created and regulated by the state.
4. Criticism of Pragmatism and Utilitarianism: Utilitarianism, which was promoted by philosophers like John Stuart Mill and Jeremy Bentham, stressed the significance of maximising utility or happiness as the foundation for moral and legal decisions. Philosophers like John Dewey and William James established pragmatism, which placed more emphasis on real-world applications than abstract ideas. These viewpoints questioned the natural law theory's applicability in resolving real-world moral and legal dilemmas.
5. Secularisation: Secularisation of society leads to the decline of their impact on moral and legal philosophy, during the period of enlightment. In secularised cultures, natural law theory—which often has a religious foundation faced scepticism and criticism.
6. Cultural and Moral Pluralism: Scepticism regarding the existence of universal moral principles has arisen from the growing diversity of cultures and moral ideas in contemporary civilizations. Natural law theory is criticised for failing to take into consideration the variety of moral standards and values found in many cultures and societies.
7. Historical Events: Historical events have played a significant role in the decline of the doctrine of natural law. For example, the atrocities committed in World War II led to the re-valuation of moral and legal concepts.

Despite the decline of its prominence, natural law theory continues to have an influence to various legal fields. Such as the rule of law, due process of law, procedure established by law etc.

Revival of Natural law School

Revival of natural law school took place at the end of the 19th century. There are various reasons[4]:

• There was a reaction against the legal theories which had over-emphasized the importance of positive law.
• It was realized that abstract thinking was not completely wrong.
• The positivist approach failed badly to handle the problems created by new social conditions:
   

1. Critique of Legal Positivism: Legal positivism, which emphasizes that law is enacted by human authority, has faced criticism for its incompetence in providing a solid foundation for morality and justice. Natural law offers an alternative perspective and provides a basis for evaluating legal norms.
2. Search for Universal Ethics: In the globalized world with diverse cultural and legal traditions, there is a need for common ground for moral principles that can apply universally. Natural law theory provides a framework for discussing ethical issues that are not bound by particular cultural or religious beliefs.
3. Religious Influence: Natural law theory has historically been intertwined with religious thought, particularly in the Christian tradition. The revival of interest in natural law may also be influenced by religious scholars and communities seeking to engage with contemporary moral and legal issues from a theological perspective.
4. Legal and Political Challenges: Challenges such as human rights abuses, environmental degradation, and social injustices have prompted scholars and activists to reevaluate existing legal frameworks and explore alternative approaches to addressing these issues. Natural law theory offers a normative framework for critiquing unjust laws and advocating for legal reform grounded in moral principles.

Role Of Authors In 19th Century To Revive The Doctrine Of Natural Law:

• Jean Dabin: The law of nature was deduced from the nature of man as it reveals itself in the basic inclination of that nature under the control of reason. As human nature is identical in people everywhere, the concepts of natural law are universal despite the geographical and other variations.
• Stammler: Law as the species of will, others-regarding, self-authoritative and inviolable. Just law is the highest expression of man. He distinguished between technical legal science and theoretical legal science. Former concern with a given legal system and deals with the content of law, latter concerned with the rule giving effect to fundamental principles.
• Fuller: There is a need for the rule of law to comply with internal morality. He made a distinction between morality of duty and morality of aspiration. To be a valid law it has to pass the test of morality and there is an inherent relation between law and morality.
• Morality of duty: Relates to external morality of law. It consists of those fundamental rules without which society cannot exist.
• Morality of aspiration: The desired norm of human conduct which would seek to promote his best interest.

Theories of natural law played a crucial role in the development of law. Plethora of principles of natural law are incorporated into the constitution of various countries. For example the USA, UK, India etc. The fundamental rights enshrined in part three of the constitution of India are highly influenced by the doctrine of natural law. The principle of natural justice is incorporated under article 311 of the constitution[5] of India which provides no civil servant can be terminated from his post without giving him a reasonable opportunity of show cause notice.

Ideas of natural justice have become more important and have been relied on by the Supreme Court and High Courts of India in its decisions. In A.K Kraipak v/s Union of India[6], the Supreme Court held that the aim of the rules of natural justice was to secure justice and to prevent miscarriage of justice. These rules can only be applied in the absence of law to a particular area.

Maneka Gandhi v/s Union of India[7], the Supreme Court observed that natural justice is a great humanizing principle intended to apply the law with fairness and to secure justice. Further directed that the law established by the state should be just, fair and reasonable.

Conclusion
There are various variations on the idea of natural law. The concept originated with the ancient Greeks, who believed that the natural law was the supreme law that applied to all eras and that it regulated the cosmos in an everlasting and unchanging manner. Even in the 19th century, when natural law began to deteriorate, it became clear that positivism was not the answer to every issue and that natural law was the better option. A natural law school was later established following the devastating effects of the World Wars. The circumstances following World War II led to the adoption of the UDHR. There are a several ideas on natural law. For example, some academics hold that morality is necessary for an individual to exist in society, while others refer to it by a different term.

End-Notes:

• Natural law theory, available at: https://www.slideshare.net/abhinandanray/natural-law-29762123 (last visited on 15th April 2024)
• Natural law theories, available at: https://lawbhoomi.com/natural-law-school-theories/#What_is_Natural_Law_School (last visited on 15th April 2024)
• V.D Mahajan's, Jurisprudence & Legal Theory 595-617 (5th ed, EBC, Ahemdabad, 2018)
• Ibid at 618
• The Constitution of India, art 311
• AIR 1970 SC 150
• AIR 1978 SC 597