Legal Literacy- This article discusses the importance of legal principles and the principle of legality in the Indonesian legal system, especially in the implementation of criminal law. The author explains in detail the laws and regulations that form the basis for law enforcement agencies in carrying out their functions, duties, authorities and responsibilities in implementing the principle of the rule of law. In addition, the author also discusses the legal principles that serve as boundaries in providing legal certainty.

Law enforcement (law enforcement) is one of the characteristics that reflects that Indonesia is a state based on law (Article 1 Paragraph 3 of the 1945 Constitution) in order to guarantee the supremacy of law for the administration of the state through statutory regulations as a basis for law enforcement agencies in carrying out their functions, duties, authorities and responsibilities in implementing the principle of the rule of law (rechtsstaat).

One form of implementation of applicable substantive law is the existence of formal law administration instruments. In the context of criminal law, in general, criminal justice proceedings are carried out based on Law Number 8 of 1981 concerning the Criminal Procedure Code (KUHAP) as the parent source of criminal justice procedural law in Indonesia.

Basically, criminal procedure law or criminal law formal is a series of overall legal instruments that regulate the procedures, procedures and mechanisms for administering criminal justice practices as an effort to maintain and enforce substantive criminal law. In other words, criminal procedure law is the constitutional basis for law enforcement officials in carrying out their duties, functions and responsibilities as well as their authorities based on the provisions as outlined in criminal procedure law.

However, it should also be noted that the KUHAP does not “suddenly” (read: immediately) apply on its own and become a guideline for all criminal justice sub-systems without strong foundations underlying it. Like a house, the foundation has an important role in strengthening the walls of the building. This also applies to the legal principles that are the guidelines and foundation for the formation of Law Number 8 of 1981 concerning Criminal Procedure Law as we are studying today.