Legal positivism is a philosophy of law that emphasizes the conventional nature of law – that it is socially constructed. According to legal positivism, the law is synonymous with positive norms, that is, norms established by Parliament or considered common law or jurisprudence. Formal criteria of origin of the law, application of the law and legal validity are sufficient to consider social norms as law. Legal positivism does not base law on divine commandments, reason, or human rights. As a historical issue, positivism arose in opposition to the classical theory of natural law, according to which there are moral limits necessary to the content of law. This term is also sometimes used to refer to legal philosophy-legal positivism, as opposed to schools of natural law and legal realism. In this sense, the term is often used in reference to the United States Code, parts of which reformulate acts of Congress (i.e. positive law), while other parts have been enacted themselves and are therefore positive law. [ref. needed] The word „positivism” was probably used to draw attention to the idea that the law is „positive” or „postulated,” as opposed to „natural” in the sense that it is derived from natural law or morality. Thomas Aquinas has little difficulty with the idea of both divine positive law and human positive law, for he does not impose any requirements on the person who establishes a law that excludes neither humans nor the divine.  For other philosophers, however, the idea of divine and human positive law has proven to be a stumbling block.
Thomas Hobbes and John Austin both embraced the idea of the ultimate sovereign. While Thomism (and indeed Mackenzie) divided sovereignty into the spiritual (God) and the temporal (Mackenzie`s „supreme power” in the state), both Hobbes and Austin sought a single, indivisible ruler as the ultimate source of law. The problem that causes this is that a temporal ruler cannot exist if people are subject to a divine positive law, but if God`s positive law does not apply to all people, then God cannot be sovereign either. The response of Hobbes and Austin is to deny the existence of positive divine law and to invest sovereignty in those who are subject to divine natural law. Worldly authority is sovereign and responsible for translating divine natural law into positive human law.  Niklas Luhmann says: „We can reduce. Positive right to a formula according to which the law is not only postulated (i.e. chosen) by decision, but is also valid by the power of decision (i.e. contingent and variable).  Positivists, however, do not claim that the law is made valid by anyone`s decision. According to Hart, the validity of the law is a matter of usual and collective court practice.
As for the moral validity of the law, positivists and realists claim that it is a matter of moral principles. „Decision-making power” plays no essential role in either, since individual choices are rarely sufficient to create a social practice of recognition, and it would be implausible to assume that moral principles are established in this way by anyone`s decision.   [ref. Legal positivism in Germany was rejected by Gustav Radbruch in 1946, when the persecution of Nazi partisans faced the challenge of judging acts compatible with Nazi German law. Radbruch argued that when „the gap between positive law and justice reaches such an intolerable level,” it effectively becomes a „false right” and should not be followed unconditionally. These internal principles, according to Fuller, constitute morality because law necessarily has positive moral value in two ways: (1) law contributes to a state of social order, and (2) does so by respecting human autonomy because rules guide behavior. Since no set of rules can achieve these morally valid goals without adhering at least to the principles of legality, Fuller argues that they constitute morality. Since these moral principles are integrated into the conditions of existence of the law, they are internal and therefore represent a conceptual link between law and morality incompatible with the theory of separability.
Thomas Aquinas mixed artificial law (lex humana) and positive law (lex posita or ius positivum).    However, there is a subtle difference between them. While man-made law considers law from the position of its origins (i.e. who postulated it), positive law considers law from the point of view of its legitimacy. Positive law is law by the will of the one who made it, and therefore there can be a divine positive law just as there is a positive law made by man. The theory of positive law comes from the powers that promulgated it. This type of law is necessary because it is man-made or promulgated by the state to protect the rights of individuals, the governed, resolve civil disputes and, finally, maintain order and security in society. (Translated more literally, lex posita is postulated rather than positive law.)  In the Summa contra Gentiles, Thomas himself writes about the divine positive law, where he says: „Si autem lex sit divinitus posita, auctoritate divina dispensatio fieri potest (if the law is divinely given, the dispensation may be granted by divine authority)” and „Lex autem a Deo posita est (But the law was established by God)”.  Martin Luther, like Juan de Torquemada, recognized the idea of divine positive law.  In a broader sense, various philosophers have advanced theories that oppose the value of positive law to natural law.
Normative legal theory, as advocated by the Brno School, gave priority to positive law because of its rational character. Classical liberal and libertarian philosophers generally prefer natural law to legal positivism. For the French philosopher Jean-Jacques Rousseau, positive law is the absence of internal obstacles. [ref. needed] Among the leading proponents of legal positivism in the twentieth century was Hans Kelsen, both in his European years before 1940 and in his American years after 1940 until his death in 1973. Thomas Mackenzie divided law into four parts, with two types of positive law: divine positive law, natural law, positive law of independent states, and the law of nations.  The first, the positive divine law, „concerns the duties of religion” and flows from revelation. He opposed it to the divine law of nature, which „is known by reason alone, without the aid of revelation.”  The third, the positive law of independent states, is the law established by the „supreme power in the state.” In other words, it is a positive man-made right.
 The fourth, international law, regulates „independent states in relations with each other.”  James Bernard Murphy explains: „Although our philosophers often try to use the term positively to specifically delineate human right, the term and concept are not well suited to do so. All of God`s law is positive in the source, and much of it is positive in content.  John Finnis` (1980) neo-naturalism is linked to Blackstone`s classical naturalism. Finnis believes that the naturalism of Thomas Aquinas and Blackstone should not be interpreted as a conceptual representation of the conditions of existence of law. According to Finnis (see also Bix, 1996), classical naturalists were not concerned with providing a conceptual representation of legal validity; rather, they were concerned with explaining the moral power of law: „The principles of natural law explain the binding force (in the fullest sense of `obligation`) of positive laws, even if these laws cannot be derived from these principles” (Finnis 1980, pp. 23-24). According to Finnis` view of the overlap theory, the essential function of law is to provide a justification for state coercion. As a result, an unjust law may be valid but may not provide sufficient justification for the use of coercive power of the State and is therefore not fully mandatory; Thus, an unjust law does not realize the moral ideals implicit in the concept of law.
From this point of view, an unjust law is legally binding, but not completely. The concept of positive law differs from „natural law”, which includes inherent rights conferred not by a legislative act, but by „God, nature or reason”.  Positive law is also described as the law that applies to a particular time (present or past) and place, composed of legal law and case law, insofar as it is binding. More specifically, positive law can be characterized as „the law actually and specifically adopted or adopted by the authority competent for the government of an organized legal society”.  Legalism deals with the area between political theory and jurisprudence. Its purpose is to bridge the intellectual gap between jurisprudence and other types of social theory by explaining why, according to historians and political theorists, legalism has failed in both its approach to morality and politics. Judith Shklar suggests that instead of viewing law as a separate entity based on a rigid system of definitions, legal theorists should treat it, along with morality and politics, as part of a global social continuum.