As the legislative principle of ‘ignorantia juris non excusat’ was replaced by criminal precedents acknowledging that ‘an inevitable legal mistake may negate culpability’, the justice of criminal law embodied by the principle of liability has gradually become a critical ‘foundation’ on which States initiate their right to punish. Against such a background, the issue of ‘legal but irrational’ or ‘rational but illegal’ in a series of recent cases of criminal law assessment reflects the ‘conflict between the authority of criminal law and the justice of criminal law, or, in other words, the conflict between the utilitarian value of criminal law and the principle of liability’. However, the relationship between utilitarian value of criminal law and the principle of liability is not that of absolutely antimony, but that of mutual dependency and mutual promotion. Meanwhile, the conflict also shows that the principle of ‘ignorantia juris non excusat’ that Chinese criminal legislation has been adhering to is outdated. Therefore, it is necessary for the Chiense legislature to provide in the General Provisions of Criminal Law that mistakes in relation to prohibition shall negate or reduce liability.