Defining the scope of criminal law and legitimated level of intervention through criminal law over the rights and freedom of citizens as the most serious kind of such intervention, is a complicated and difficult matter. The principle of criminal law as the last and the least resort as a basic principle of this knowledge, technique and instrument of social control, as emphasizes upon the destructive results of abuse of penal concepts, instruments and institutions, tries to detennine the appropriate level of intervention through criminal law and provide the possibility of usage for other kinds of social control instruments and institutions. This article, as emphasizes upon the necessity of considering this principle in more details, will discuss the concepts, basics and implications of this principle for penal policy (criminalization and penalization).