The Principle of Legality in the Criminal Law of the U.S.A

Extremely important in modern criminal law,Nullum crimen,sine lege,nulla poena sine lege is also called or the principle of legality in U.S.A criminal law.This paper mainly discusses its real meaning,its necessity as proved by American scholars,its embodiment in the constitution and criminal law of U.S.A,its characteristics,its position and the basic values it intends to advocate.