This refers to the basic legal principles upon which national legal systems are based and which provide a framework within which national laws are made and powers are exercised. These fundamental principles are normally contained or expressed within a national Constitution or similar document, or through decisions of the highest level of court having the power to make binding interpretations or determinations of national law. Although it will vary from country to country.
Some examples of such fundamental principles include rights of due process, the presumption of innocence, and a person’s right to effective protection by the courts.