Achieving a fair trial and achieving common and specific goals of criminal law requires the observance of some substantive and formal rules based on rational principles or general principles. The primary and important purpose of these principles is to guarantee individual rights and freedoms. One of these essential principles is the principle of interpretation in favor of the accused in the position of interpretation of formal and substantive rules, which is first matured in the domestic criminal law of countries and then transferred to international criminal law as a certain value of all penal systems. In this article, an attempt has been made to explain the scope and scope of citing this principle in the interpretations of criminal regulations. Of course, the implementation of the principle includes challenges that, observing the rights of victims, paying special attention to the dangerous situation for some criminals and protecting the rights of society are the most important obstacles to the application of this principle in general. In international criminal courts, due to the special nature of their creative origin, the mentioned principle has been accompanied by changes in practice, and in the issued verdicts, citing obstacles to this interpretation, the defendant's profit has sometimes been ignored. Comparing Iranian law with international criminal law, it can be said that the principle of innocence, the principle of legality of crime and punishment is one of the most important theoretical foundations of interpretation in favor of the accused.