Basic objective of this article is to define and discuss on Nature of Criminal Law. Criminal law encompasses both substantive prison law and criminal procedure. Substantive law defines proscribed actions and specifies penalties. Legal guidelines concerning murder, rape, and robbery are substantive for the reason that they define unlawful acts. Procedural law consists of rules stating the fact that government proceeds against somebody accused of committing any crime. Trial by jury, the right to advice, the right to attractiveness, and the right to take care of one’s accusers are only a few examples of procedural regulation.