CLS tries to influence social reality. The existing structure is the use of beliefs and assumptions that create a society in the reality of relationships between people. Such belief structures or ideologies have the potential to be obscured in their tendency to maintain their own momentum to create legal doctrines that blame conditions and nature. For critical legal studies, legal consciousness is a tool that deals with the mind to carry out oppression. It is a way of hiding the fundamental truth or avoiding that everything is in a process of change and presence. Critical legal studies to understand social reality and the legal system and the commitment to develop a legal theory based on social practice to revise the hierarchical social structure are the main advantages of critical legal studies. This power manifests itself in the form of a critical analysis of the legal system, values and legal relations of judges, which have always been described as neutral and objectively correct. The benefits of critical legal studies consist of different types of thinking put forward by many legal experts. These thoughts vary from thought shaped by orthodox Marxists to postmodern thought. There is some understanding between these ideas, namely distrust of legal neutrality, hierarchically and ideologically dominated social structures of certain groups, and the desire to revise social structures.
The development of this school of legal positivism has reinforced the lesson of legism, a lesson that holds that there is no law outside of legislation, since law is the only source of law. Laws and laws are identified. This legal thought of legism has developed since the Middle Ages and was influential in many states before the beginning of legal positivism. However, legal lawmaking is not the same as legal positivism. If experts in legalism consider only law as the source of law, then experts in legal positivism limit it not only to law as the source of law, but also to the customs, manners and opinions of society. Experts in legal positivism argue that the scientific work of jurists concerns only positive law, but that it can be guided by natural law or higher law, as do proponents of natural law. However, this separation of morality and laws in positivism was later criticized by L.L. Fuller, who explained that a legal system aims to guide human behaviour and control general rules; which must follow certain standard procedures. Fuller explained that in addition to external morality, there is also an internal morality that serves as a good lawmaker, that is, the law must: 1) be general; (2) promulgated; (3) it should not be retroactive; 4) Be clear; (5) do not contradict each other; (6) can be tested; (7) has not changed rapidly; and (8) as a result between the Standard Rules and their implementation.
Inner morality is actually a moral aspiration. If a system cannot meet all eight requirements, as Fuller intended, then the law is considered invalid in people`s lives. The law must involve moral values to be applied fairly. Fuller`s thought is a response or critique of Hart`s thought. Fuller is considered a lawyer who has an opinion on the importance of morality in law. This morality must be respected if the creator of the rules wants to establish the rule of law, even if the rule of law is very bad. There are two definitions of morality that include law, namely external morality and internal morality. External morality implies that the regulatory authority must be supported by moral behavior related to the requisite competence, while internal morality is a morality that exists in the law itself.
Fuller`s dissent or criticism of Hart and other thinkers of legal positivism is illustrated in light of Nazi Germany`s supposedly cruel penal system and was in effect from the 1930s until the end of World War II.
