1. What is the purpose of criminal law? 2. What are the various categories and classes of crimes? 3. What is the nature of an act according to the meaning of criminal liability? 4. What are the four mental states that can be found in the criminal code? Solution 1. Porpuse of criminal law to keep order in society and lessen the harm individuals may cause to one another Reference: http://enlightenme.com/criminal-laws/ 2. What are the various categoires and classes of crimes? Personal Crimes.