The basis of the Natural Law Theory is that there exist laws above man which can be discovered through reason and which are derived from objective moral principles and the essential nature of the world. The term ‘natural law’ has, however, been interpreted differently at different times. Early Christian writers scoured the scriptures to find these laws. However, in the 17^th century, Grotius significantly secularised the concept of natural law by bringing reason into the picture.

What has always been agreed though is that it is not the creation of a temporal political authority. Other characteristics of natural law are that:
1. It is binding on all men everywhere at all times.
2. It is not written.
3. It advocates the equality of men.
4. The rule of law can be studied on an a priori basis.

Further, unlike other laws:
1. It is rigid, immutable, eternal and unalterable.
2. It is not enforceable by an external agency; there is no coercive sanction which backs it.
3. It is not the creation of an act of legislature, it is the result of the teachings of various philosophers.
4. It is unwritten and has not been made by men; all men have done is discover it.

Human law was considered to truly be law only insofar as it conformed to the principles of natural law on one hand. And on the other, law was considered to be law only if it was obligatory. Since natural law was considered higher than human law, any human law contrary to (the principles of justice and morality which are inseparably entwined with) natural law was not really considered to be law at all.

The problem, however, was discovering natural law itself. Enquiries into the realm of natural law began with the Greek philosophers as a challenge to the arbitrariness and the obligatory nature of law itself.

The Ancient Period

Socrates examined key moral concepts such as the Good and Justice. He said that ‘virtue was the most valuable of all possessions; the ideal life was spent in search of the Good. Truth lies beneath the shadows of existence, and that it is the job of the philosopher to show the rest how little they really know’. His pupil, Plato, said that justice lies in integrating reason and wisdom in man’s life.

It was noticed that while there are some occurrences, like the movements of heavenly bodies, were regulated by nature while others, like human etiquette, depended entirely on human choice and were arbitrary. This arbitrariness encouraged philosophers to question why law should be obeyed at all. However, Aristotle pointed out that there were some human laws which were common to all human States (such as the inviolability of heralds) and therefore, by extension, it was natural for humans to have those human laws.

The theory was further developed by the Stoic Philosophers.

Later, the Roman lawyer, Cicero, said that ‘true law is right reason in agreement with nature, it is of universal application, unchanging and everlasting’. It is created by the reason of intelligence of man whose ability to reason enables him to stand highest in creation.

The Medieval Period

The Medieval Period began around the 11^th century and continued till the 13^th century. It boasted mainly Christian theologians like Thomas Aquinas, Gregory and Ambrose.

St Thomas Aquinas divided law into:
1. The Law of God
2. Natural Law Natural law is created by man’s reason – the sole repository of mans’ social life – and governs human relations; his approach was empirical.
3. Divine/Scriptural law The church if the supreme authority to interpret divine law
4. Human Law It must be based on natural law and aim to do good.

Aquinas spoke of Eternal Law which, for all practical purposes, was the same as natural law. He said that everything is governed by God’s eternal law but man can choose whether or not to follow the law.

Christian theologians also managed to combine pre-Christian philosophy into their own theology with the aid of St Paul who had said that the conscience could arrive at moral truth unaided. For example, Aquinas wrote thirteen commentaries on Aristotle and resolved conflicts by assigning two different meanings – a Christian one and an Aristotelian one – to the same term and saying that such differences evidence true philosophical inquiry.

The Renaissance and the Age of Enlightenment

The Renaissance began around the 14^th century and continued till the end of the 16^th century. It was followed by The Age of Enlightenment. The dependence on God waned during this time and the authority of the Church diminished. By the 17^th century, thanks to the work of scholars like Grotius, philosophers like Hobbes and Locke spoke of man’s rights and natural law in the same breath.

Thomas Hobbes (1588-1679) said that law is the dictate of right reason.

John Locke (1632-1704) said that natural law supported the individual against the absolute power of the sovereign. All government is a fiduciary trust which is dissolved when law is violated or power is abused. In his version of the social contract theory, individuals have inalienable natural rights and their duties are defined in terms of protecting their own rights and respecting those of others. They may revolt against the government if the government betrays its trust. Sovereigns are bound by natural law which Locke described as ‘reason’.

Jean Rousseau (1712-1778) published The Social Contract in 1762. He said that man was forced to adopt institutions of law to survive because the state of nature degenerated. Individuals therefore collectively parted with their natural rights to preserve themselves and remain free; they received civil liberties in exchange of natural rights. The State and law are therefore both the result of and subject to the General Will of the people.

None of this established what natural law is though.

The Modern Period

The 19^th century saw a decline in the influence of the natural law theory and an increase in the influence of theories put forward by various other schools such as the analytical, sociological and historical schools.

Bentham called natural law nonsense on stilts though and said that it was the result of confusing scientific laws from moral and legal laws. To the Greeks, watching the movements of heavenly bodies and other natural phenomena, it seemed that every object had a purpose. There is a defence to this: it could be argued that scientific laws too merely describe the way in which things should occur, the way in which they have been pre-ordained to occur. The question then, of course, would be pre-ordained by whom? A Creator? God? The result would be that one would have to prove the existence of God – no easy task.

Auguste Comte said that the natural law theory was false, non-scientific and based on a belief in the supernatural.

David Hume used analytical positivism to destroy the theoretical basis of the natural law theory which he said was vague and obscure.

The 20th century, however, saw a revival in the natural law theory. This was mainly because people did not want to divorce law from morality, customs and religion. In any case, concepts like those of equality and justice which were inherent in the natural law theory were also the foundation of positivism. In addition to this, after the devastation caused by the two World Wars, the West wanted a value-conscious theory of law.

The obvious ‘advantages’ of the natural law theory are that it links law to justice and morality. The problem with that is that and questions of morality are not open to adjudication. Also, law, as we know it today, relies heavily on precedent and on Statutes. Courts generally do not decide disputes ex aequo et bono and if they did, the result would be that it would be impossible to predict a legal decision.