Many Acts are given the form of framework laws containing general guidelines and leaving it to the minister concerned to provide more precise regulations. Such provisions are often supplemented by government circulars, i.e. rules directed solely at the authorities. An Act is amended or repealed by a new Act being passed. They consist of up-dated law texts consisting of the relevant parts of the original Act supplemented with changes to it. From ancient times existing the contents of the law have moreover been determined by the courts by means of case law in areas where there is no legislation, and this still occurs, for instance especially in the law of compensation.
Customary law are also sources of law.
A legal custom arises when a specific manner of behaviour has been followed generally, constantly and over a long period of time, because the persons concerned were convinced that they were legally obliged to do so. Such legal customs are deemed part of the law of the land. They can be set aside by legislation, or the courts can overrule them as unreasonable. The legal norms that govern the relationship between states are called international law. In Denmark the government has the authority to act on behalf of the country in international legal matters, including the authority to enter into internationally binding agreements by treaty.