摘要： 如所周知，中外刑法由于法律文化传统、法律演进路径的不同而形成不同的犯罪定量模式，即西方国家一般实行“司法定量”模式而中国则实行“立法定量”模式。“立法定量”模式是实质主义刑法观的产物，虽然具有实质合理性，符合刑法谦抑原则，但是欠缺形式合理性，从而带来一系列问题。因此，放弃立法定量，实行司法定量，并构建轻罪处理机制，是理性选择。

关键词: 但书规定, 立法定量, 司法定量, 轻罪处理机制

Abstract: Known to all of us，the Penal Law of China has developed a different criminal quantitative mode fromthose of foreign countries because of different legal cultural tradition and legal developing path，The westerncountries take generally the judicial quantitative mode and China takes the legislative quantitative mode，thelatter is the product of substantial theories of criminal law. In spite of being rational substantially and consistent with the principle of restraining criminal law，the legislative quantitative mode is deficient in formal rationality and results in such problems as：Firstly，it is very difficult technically in legislation，that is，thelegislative body cannot outline clearly the severity of crimes；Secondly，it will confuse judicially the boundary of crime and noncrime，or of criminal illegality and other illegalities and affect the realization of the principle of legality；Thirdly，it is difficult to position properly the element of criminal severity in the system ofthe constitution of crime；Finally，it will result in omissions of the system of criminal law and be adverse tocrime prevention and establishment of social basic morality. Therefore，it is a rational choice to give up thelegislative quantitative mode，take the judicial quantitative one and set up the disposition mechanism of minor offeuses.

Key words: Proviso, Legislative Quantitative Mode, Judicial Quantitative Mode, Disposition Mechanism of Minor Offenses