The first problem with the positive-law system is the inability to distinguish between laws and natural justice. Despite this, human beings have always sought to define their own rules. For instance, the Greek city-states established social hierarchy and subordinated women to men and slaves to citizens. Throughout the history of civilization, people have attempted to establish their own laws, arguing that they are more real and meaningful than the ones created by law and nature.
The second problem with positive law is that it requires an omnipotent ruler to create it. This is why a governmental body has the power to impose certain laws, including natural law. In other words, the government must enact a law to make the people live in peace. This is not true with the natural-law system. The only way to have a good society is to have a good legal system.
Safety of society
The Brno school of law defined natural law as something that contributes to the well-being and safety of society. The concept of legal positivism is also referred to as soft positivism, and is favored by classical liberals and libertarians. The French philosopher Jean-Jacques Rousseau was the first to define positive law, and the most prominent proponent of legal positivism in the twentieth century was Hans Kelsen. The neo-Natalist, Francois Geny, introduced the notion of free scientific research into positive-law theory.