The principle of a legally prescribed punishment for a crime means that there is no explicit stipulation that it is not a crime and there is no explicit stipulation that it will not be punished. The basic requirements are legalization, certainty and clarity. The principle of a legally prescribed punishment for a crime can be divided into the principle of absolute crime and the principle of relative crime. The legal punishment of absolute crime completely excludes the judge's discretion, and the judge should apply the criminal law word for word, while the legal punishment of relative crime can accommodate the judicial discretion to a certain extent.

Its basic content is:

(1) It is absolutely forbidden to apply analogy, but it is not forbidden to expand interpretation. The criminal law clearly stipulates that it is the only basis for conviction. Acts that are not expressly stipulated in the law cannot be treated as crimes by analogy or analogy.

(2) The application of customary law is absolutely prohibited, and written law is the only source of criminal law. Customary law is not allowed to be used to convict an act that is not explicitly stipulated in the criminal law.

(3) The retroactivity of criminal law is absolutely forbidden, and following the old principle is the only principle to solve the problem of retroactivity of criminal law. The conviction and sentencing of an act can only be based on the law in force at that time, and the new law promulgated after the act has no retrospective effect.

(4) Extrajudicial punishment and indefinite punishment are absolutely prohibited. The name, type and scope of punishment must be determined by law, and the term of imprisonment must be absolutely determined. Neither absolute life imprisonment nor relative life imprisonment is allowed.