Criminology and criminal law both are interlinked and interrelated to each other. Criminology deals with the psychology of law and criminal law deal with the crime itself.
Criminal Policy is the name given to that branch of criminal science that studies the means by which the volume of harmful conduct in society can be limited. It makes use of the information provided by criminology, and its subjects for the investigation, therefore, are (a) the appropriate measures of social organisation whereby harmful activities may be prevented, and (b) the treatment to be accorded to those who have caused harm.
Criminology is concerned with the causes of crime and comprises (a) criminal biology, which investigates causes of criminality that may be found in the mental and physical constitution of the delinquent himself, such as hereditary tendencies and physical defects, (b) criminal sociology, which deals with enquiries into the effect of an environment as a cause of criminality.
The Criminal law involves the decisions as to which violations can be appropriately left in the class of torts, to be redressed by civil actions for compensation brought by the victim, and which need to be dealt with by the special sanctions imposed by criminal law and further which of those sanctions are appropriate in each case. These range from the penalty of death, through various degrees of deprivation of liberty down to such measures as medical treatment, supervision on probation, and mere warnings. Since it is criminal policy which must dictate the principles by which harms are to be classed as crime and criminals are to be detected and treated, it is clear that criminal law which forms the third branch of criminal science, is the instrument of criminal policy.
Criminal law and criminology both are related to each other. They both are interlinked. Both criminal law and criminology are required for lawyers and law enforcement agencies who deal with the psychology of criminals and various aspects related to crimes. Criminologists basically focus on the pattern, behaviour and sociological aspects of crimes. They tend to observe the patterns in criminal behaviour.
Criminal justice is an established legal system that investigates crimes, arrests criminals, detains them and prosecutes the guilty ones. Criminal law is directly interlinked to law enforcement agencies because their primary work is to detect the crimes and arrest the people who are suspected of committing any offence. Criminology, on the other hand, is the detailed study of the root cause of the crimes, its origin and also the psychological tendencies of a criminal and the effect of crimes on society and on various parameters.
Criminal law and criminology are the masters of their own respective domains. They have their own specific niche. Criminal law is associated with the judicial and criminal justice system, juvenile justice system, law enforcement agencies and with correctional institutions such as prisons and rehabilitation centres. The main objective of criminal law is to arrest the criminals and to provide justice to the justice seekers. It works on a fixed principle.