In his most famous novel, The Red and the Black, the French author Stendhal wrote

Natural law maintains that the inborn moral standards should form the basis of our society in terms of laws and morals. Further,
natural law is not taught in any school and human beings just discover it (Priel, 2008)
The use of natural law may not make a lot of sense because human beings morals and the ability to discern what is wrong and right depends on circumstances for example the social and cultural factors. Meaning that something may me right in a particular society but be termed as wrong in another one.
Positive law or what is termed as man-made law found in constitutions, statutes or in common law (Priel, 2008). Legal realism and positive law hold that the law is a product of human beings in the context of the surroundings and society which may or may not conform to natural Law (Leiter, 2001).
References
Leiter, B. (2001). Legal Realism and Legal Positivism Reconsidered. Ethics, 111(2), 278-301. doi:10.1086/233474
Priel, D. (2008). Were the Legal Realists Legal Positivists? Law and Philosophy, 27(4), 309-350
 
Researchers and scientists have over time developed so many theories in eort to understand the concepts of law which is an important component in any given nation (Leiter, 2001). Natural law is one among the theories which is based on ethics and a belief that human beings have inborn values that guide and govern their behavior and reasoning. It also holds that the aspect of discerning what is right and wrong is purely inherent and it cannot be created by either court or society