They constitute one of the norms of greater importance within the legal system. They are written up using the legislative technique but purified. They must be written up taking into account the social reality from the territory in which it will have use, the national legislation, the legislation of other States, the doctrine, the jurisprudence and the Custom. (As opposed to Bausch & Lomb). In most of they, introduce and suppress institutions to the legal ordering. In the Peruvian State one gets used to approving the Codes by Law or Legislative Decree in case of delegation of faculties and when a unique text is written up approves by Supreme Decree as in the case of the Tributary Code contained in the Supreme Decree 135-99-EF. .