INTRODUCTION
Natural Law
Is a philosophy of law that is determined by nature, and so is unive rsal. Classically, natural law refers to the use of reason to analyze human nature both social and personal and deduce binding rules of moral behavior from it. Natural law is often contrasted with the positive law of a given political community, society, or state. In legal theory, on the other hand, the interpretation of positive law requires some reference to natural law
Although natural law is often conflated with common law, the two are distinct in that natural law is a view that certain rights or values are inherent in or universally cognizable by virtue of human reason or human nature, while common law is the legal tradition whereby certain rights or values are legally cognizable by virtue of judicial recognition or articulation
PROPONENTS OF NATURAL LAW
Plato
According to Plato we live in an orderly universe. At the basis of this orderly universe or nature are the forms, most fundamentally the Form of the Good, which Plato describes as "the brightest region of Being". The Form of the Good is the cause of all things and when it is seen it leads a person to act wisely. In the Symposium, the Good is closely identified with the Beautiful. Also in the Symposium, Plato describes how the experience of the Beautiful by Socrates enables him to resist the temptations of wealth and sex. In the Republic, the ideal community is, "...a city which would be established in accordance with nature.
Aristotle
Greek philosophy emphasized the distinction between "nature" (physis) on the one hand and "law", "custom", or "convention" (nomos, νóμος) on the other. is often said to be the father of natural law
Aristotle's association with natural law may be due to the interpretation given to his works by Thomas Aquinas. But whether Aquinas correctly read Aristotle is a disputed question. According to some, Aquinas conflates the natural law and natural right, the latter of which Aristotle posits in Book V of the Nicomachean Ethics (Book IV of the Eudemian Ethics). According to this interpretation, Aquinas's influence was such as to affect a number of early translations of these passages in an unfortunate manner, though more recent translations render them more literally. Aristotle notes that natural justice is a species of political justice, the scheme of distributive and corrective justice that would be established under the best political community; were this to take the form of law, this could be called a natural law, though Aristotle does not discuss this and suggests in the Politics that the best regime may not rule by law at all.
The best evidence of Aristotle's having thought there was a natural law comes from the Rhetoric, where Aristotle notes that, aside from the "particular" laws that each people has set up for itself, there is a "common" law that is according to nature. Specifically, he quotes Sophocles and Empedocles:
The Stoics ;Stoic natural law
The development of this tradition of natural justice into one of natural law is usually attributed to the Stoics. The rise of natural law as a universal system coincided with the rise of large empires and kingdoms in the Greek world. Whereas the "higher" law Aristotle suggested one could appeal to was emphatically natural, in contradistinction to being the result of divine positive legislation, the Stoic natural law was indifferent to the divine or natural source of the law: the Stoics asserted the existence of a rational and purposeful order to the universe (a divine or eternal law), and the means by which a rational being lived in accordance with this order was the natural law, which spelled out action that accorded with virtue.[1]
Natural law first appeared among the stoics who believed that God is everywhere and in everyone. Within humans is a "divine spark" which helps them to live in accordance with nature. The stoics felt that there was a way in which the universe had been designed and natural law helped us to harmonize with this.
Marcus Tullius Cicero
Cicero wrote in his De Legibus that both justice and law derive their origin from what nature has given to man, from what the human mind embraces, from the function of man, and from what serves to unite humanity. For Cicero, natural law obliges us to contribute to the general good of the larger society. The purpose of positive laws is to provide for "the safety of citizens, the preservation of states, and the tranquility and happiness of human life." In this view, "wicked and unjust statutes" are "anything but 'laws,'" because "in the very definition of the term 'law' there inheres the idea and principle of choosing what is just and true." Law, for Cicero, "ought to be a reformer of vice and an incentive to virtue." Cicero expressed the view that "the virtues which we ought to cultivate, always tend to our own happiness, and that the best means of promoting them consists in living with men in that perfect union and charity which are cemented by mutual benefits."
Cicero influenced the discussion of natural law for many centuries to come, up through the era of the American Revolution. The jurisprudence of the Roman Empire was rooted in Cicero, who held "an extraordinary grip ... upon the imagination of posterity" as "the medium for the propagation of those ideas which informed the law and institutions of the empire." Cicero's conception of natural law "found its way to later centuries notably through the writings of Saint Isidore of Seville and the Decretum of Gratian." Thomas Aquinas, in his summary of medieval natural law, quoted Cicero's statement that "nature" and "custom" were the sources of a society's laws.
Revolutionary legal scholar James Wilson. Cicero became John Adams's "foremost model of public service, republican virtue, and forensic eloquence." Adams wrote of Cicero that "as all the ages of the world have not produced a greater statesman and philosopher united in the same character, his authority should have great weight." Thomas Jefferson "first encountered Cicero as a schoolboy learning Latin, and continued to read his letters and discourses as long as he lived. He admired him as a patriot, valued his opinions as a moral philosopher, and there is little doubt that he looked upon Cicero's life, with his love of study and aristocratic country life, as a model for his own." Jefferson described Cicero as "the father of eloquence and philosophy.
Heinrich A. Rommen
Heinrich A. Rommen remarked upon "the tenacity with which the spirit of the English common law retained the conceptions of natural law and equity which it had assimilated during the Catholic Middle Ages, thanks especially to the influence of Henry de Bracton (d. 1268) and Sir John Fortescue (d. cir. 1476). Bracton's translator notes that Bracton "was a trained jurist with the principles and distinctions of Roman jurisprudence firmly in mind"; but Bracton adapted such principles to English purposes rather than copying slavishly. In particular, Bracton turned the imperial Roman maxim that "the will of the prince is law" on its head, insisting that the king is under the law. The legal historian Charles F. Mullett has noted Bracton's "ethical definition of law, his recognition of justice, and finally his devotion to natural rights." Bracton considered justice to be the "fountain-head" from which "all rights arise." For his definition of justice, Bracton quoted the twelfth-century Italian jurist Azo: "'Justice is the constant and unfailing will to give to each his right.'" Bracton's work was the second legal treatise studied by the young apprentice lawyer Thomas Jefferson.
American jurisprudence
The U.S. Declaration of Independence states that it has become necessary for the people of the United States to assume "the separate and equal station to which the Laws of Nature and of Nature's God entitle them". Some early American lawyers and judges perceived natural law as too tenuous, amorphous and evanescent a legal basis for grounding concrete rights and governmental limitations. Natural law did, however, serve as authority for legal claims and rights in some judicial decisions, legislative acts, and legal pronouncements. Robert Lowry Clinton argues that the U.S. Constitution rests on a common law foundation and the common law, in turn, rests on a classical natural law foundation.
Abū Rayhān al-Bīrūnī ; Islamic natural law
Abū Rayhān al-Bīrūnī, an Islamic scholar and polymath scientist, understood natural law as the survival of the fittest. He argued that the antagonism between human beings can only be overcome through a divine law, which he believed to have been sent through prophets. This is also the position of the Ashari school, the largest school of Sunni theology. Averroes (Ibn Rushd), in his treatise on Justice and Jihad and his commentary on Plato's Republic, writes that the human mind can know of the unlawfulness of killing and stealing and thus of the five maqasid or higher intents of the Islamic sharia or to protect religion, life, property, offspring, and reason. The concept of natural law entered the mainstream of Western culture through his Aristotelian commentaries, influencing the subsequent Averroist movement and the writings of Thomas Aquinas.

Thomas Hobbes
Thomas Hobbes founded a contractualist theory of legal positivism on what all men could agree upon: what they sought (happiness) was subject to contention, but a broad consensus could form around what they feared (violent death at the hands of another). The natural law was how a rational human being, seeking to survive and prosper, would act. Natural law, therefore, was discovered by considering humankind's natural rights, whereas previously it could be said that natural rights were discovered by considering the natural law. In Hobbes' opinion, the only way natural law could prevail was for men to submit to the commands of the sovereign. Because the ultimate source of law now comes from the sovereign, and the sovereign's decisions need not be grounded in morality, legal positivism is born. Jeremy Bentham's modifications on legal positivism further developed the theory.
According to Hobbes, there are nineteen Laws. The first two are expounded in chapter XIV of Leviathan ("of the first and second natural laws; and of contracts"); the others in chapter XV ("of other laws of nature").
Hugo Grotius
Liberal natural law grew out of the medieval Christian natural law theories and out of Hobbes' revision of natural law, sometimes in an uneasy balance of the two.
Hugo Grotius based his philosophy of international law on natural law. In particular, his writings on freedom of the seas and just war theory directly appealed to natural law. About natural law itself, he wrote that "even the will of an omnipotent being cannot change or abrogate" natural law, which "would maintain its objective validity even if we should assume the impossible, that there is no God or that he does not care for human affairs." (De iure belli ac pacis, Prolegomeni XI). This is the famous argument etiamsi daremus (non esse Deum), that made natural law no longer dependent on theology. However, German church-historians Ernst Wolf and M. Elze disagreed and claimed that Grotius' concept of natural law did have a theological basis. In Grotius' view, the Old Testament contained moral precepts (e.g. the Decalogue) which Christ confirmed and therefore were still valid. Moreover, they were useful in explaining the content of natural law. Both biblical revelation and natural law originated in God and could therefore not contradict each other.
References
• Adams, John. 1797. A Defence of the Constitutions of Government of the United States of America. 3rd edition. Philadelphia; repr. Darmstadt